400 Light & Optics MCQ Questions with Answers from Physics | Complete Quiz Bank for Competitive Exams

Light

Q1. Light is a form of:

(a) Electromagnetic radiation ✅

(b) Mechanical vibration

(c) Sound energy

(d) None

Explanation: Light consists of oscillating electric and magnetic fields that propagate through space.

Q2. The speed of light in vacuum is:

(a) 3 × 10⁸ m/s ✅

(b) 3 × 10⁶ m/s

(c) 3 × 10⁵ m/s

(d) None

Explanation: This universal constant is denoted by c and is fundamental in physics.

Q3. Light exhibits:

(a) Both wave and particle nature ✅

(b) Only wave nature

(c) Only particle nature

(d) None

Explanation: Wave–particle duality is central to quantum mechanics.

Q4. The wave theory of light was proposed by:

(a) Huygens ✅

(b) Newton

(c) Einstein

(d) Maxwell

Explanation: Huygens explained reflection and refraction using wavefronts.

Q5. The particle theory of light was proposed by:

(a) Newton ✅

(b) Huygens

(c) Einstein

(d) Planck

Explanation: Newton suggested corpuscles of light to explain straight-line propagation.

Q6. Maxwell’s theory showed that light is:

(a) Electromagnetic wave ✅

(b) Sound wave

(c) Mechanical wave

(d) None

Explanation: Maxwell unified electricity and magnetism, predicting EM waves.

Q7. Quantum theory of light was introduced by:

(a) Planck ✅

(b) Newton

(c) Huygens

(d) Maxwell

Explanation: Planck explained blackbody radiation using quantized energy packets.

Q8. Einstein explained photoelectric effect using:

(a) Photons ✅

(b) Electrons

(c) Waves only

(d) None

Explanation: Light quanta (photons) transfer energy to electrons.

Q9. The energy of a photon is given by:

(a) E = hf ✅

(b) E = mc²

(c) E = mv²

(d) None

Explanation: h = Planck’s constant, f = frequency.

Q10. The momentum of a photon is:

(a) p = h/λ ✅

(b) p = hf

(c) p = mc

(d) None

Explanation: Photon momentum relates to wavelength.

Q11. Visible light wavelength range is:

(a) 400–700 nm ✅

(b) 200–400 nm

(c) 700–1000 nm

(d) None

Explanation: Human eye detects this range.

Q12. Ultraviolet light has wavelength:

(a) < 400 nm ✅

(b) > 700 nm

(c) 400–700 nm

(d) None

Explanation: UV lies just beyond violet.

Q13. Infrared light has wavelength:

(a) > 700 nm ✅

(b) < 400 nm

(c) 400–700 nm

(d) None

Explanation: IR lies just beyond red.

Q14. X-rays have wavelength:

(a) 0.01–10 nm ✅

(b) 100–400 nm

(c) 700–1000 nm

(d) None

Explanation: X-rays are high-energy EM waves.

Q15. Gamma rays have wavelength:

(a) < 0.01 nm ✅

(b) 0.01–10 nm

(c) 100–400 nm

(d) None

Explanation: Gamma rays are most energetic EM radiation.

Q16. Scattering of light occurs due to:

(a) Interaction with particles/molecules ✅

(b) Reflection only

(c) Refraction only

(d) None

Explanation: Small particles scatter light in different directions.

Q17. Rayleigh scattering explains:

(a) Blue color of sky ✅

(b) Red color of sky

(c) White clouds

(d) None

Explanation: Shorter wavelengths scatter more, making sky appear blue.

Q18. At sunset, sky appears red because:

(a) Longer wavelengths scatter less ✅

(b) Shorter wavelengths scatter more

(c) No scattering

(d) None

Explanation: Blue light is scattered away, red dominates.

Q19. Tyndall effect is:

(a) Scattering of light by colloids ✅

(b) Reflection

(c) Refraction

(d) None

Explanation: Colloidal particles scatter light, making path visible.

Q20. Raman effect is:

(a) Inelastic scattering of light ✅

(b) Elastic scattering

(c) Reflection

(d) None

Explanation: Discovered by C.V. Raman, photons lose/gain energy.

Q21. Raman effect is used in:

(a) Spectroscopy ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Identifies molecular vibrations and structures.

Q22. Clouds appear white because:

(a) All wavelengths scatter equally ✅

(b) Only blue scatters

(c) Only red scatters

(d) None

Explanation: Large droplets scatter all colors uniformly.

Q23. The color of sea appears blue due to:

(a) Scattering and absorption ✅

(b) Reflection only

(c) Refraction only

(d) None

Explanation: Water absorbs red, scatters blue.

Q24. Fog lamps are yellow because:

(a) Longer wavelength scatters less ✅

(b) Shorter wavelength scatters more

(c) Yellow is brighter

(d) None

Explanation: Yellow penetrates fog better than blue.

Q25. The phenomenon responsible for twinkling of stars is:

(a) Atmospheric refraction and scattering ✅

(b) Reflection

(c) Diffraction

(d) None

Explanation: Light bends and scatters in turbulent atmosphere, causing twinkling.

Q26. Laws of reflection state:

(a) Angle of incidence = angle of reflection ✅

(b) Angle of incidence = 90°

(c) Angle of reflection = 0

(d) None

Explanation: Reflection follows i = r, and incident ray, reflected ray, and normal lie in the same plane.

Q27. Image formed by a plane mirror is:

(a) Virtual, erect, same size ✅

(b) Real, inverted

(c) Magnified

(d) None

Explanation: Plane mirrors always produce virtual, upright images of equal size.

Q28. Distance of image from mirror equals:

(a) Distance of object ✅

(b) Half distance

(c) Double distance

(d) None

Explanation: In plane mirrors, object and image are equidistant from mirror surface.

Q29. If a person moves 1 m towards a plane mirror, image moves:

(a) 1 m ✅

(b) 2 m

(c) 0.5 m

(d) None

Explanation: Image shifts same distance as object.

Q30. Two plane mirrors inclined at 90° produce:

(a) 3 images ✅

(b) 2 images

(c) 4 images

(d) None

Explanation: Formula: n = (360/θ) − 1. For θ = 90°, n = 3.

Q31. Two plane mirrors inclined at 60° produce:

(a) 5 images ✅

(b) 4 images

(c) 6 images

(d) None

Explanation: n = (360/θ) − 1 = (360/60) − 1 = 5.

Q32. Spherical mirror with reflecting surface curved inward is:

(a) Concave ✅

(b) Convex

(c) Plane

(d) None

Explanation: Concave mirrors converge light.

Q33. Spherical mirror with reflecting surface curved outward is:

(a) Convex ✅

(b) Concave

(c) Plane

(d) None

Explanation: Convex mirrors diverge light.

Q34. Focal length of spherical mirror is:

(a) Half radius of curvature ✅

(b) Equal to radius

(c) Double radius

(d) None

Explanation: f = R/2.

Q35. Mirror formula is:

(a) 1/f = 1/v + 1/u ✅

(b) f = v + u

(c) f = v − u

(d) None

Explanation: Relates focal length, object distance, and image distance.

Q36. Magnification formula is:

(a) M = −v/u ✅

(b) M = u/v

(c) M = f/u

(d) None

Explanation: Negative sign indicates inverted image for real cases.

Q37. Concave mirror forms real image when object is:

(a) Beyond focus ✅

(b) At focus

(c) Between focus and pole

(d) None

Explanation: Rays converge to form real image.

Q38. Concave mirror forms virtual image when object is:

(a) Between focus and pole ✅

(b) Beyond focus

(c) At center

(d) None

Explanation: Rays diverge, image appears behind mirror.

Q39. Convex mirror always forms:

(a) Virtual, erect, diminished image ✅

(b) Real, inverted

(c) Magnified

(d) None

Explanation: Convex mirrors diverge rays, image is always virtual.

Q40. Concave mirror used in:

(a) Headlights ✅

(b) Rear-view mirrors

(c) Spectacles

(d) None

Explanation: Produces parallel beam of light.

Q41. Convex mirror used in:

(a) Rear-view mirrors ✅

(b) Headlights

(c) Telescopes

(d) None

Explanation: Provides wide field of view.

Q42. If object at center of curvature of concave mirror:

(a) Image at center, same size, inverted ✅

(b) Image at focus

(c) Image at infinity

(d) None

Explanation: Symmetry about center.

Q43. If object at focus of concave mirror:

(a) Image at infinity ✅

(b) Image at center

(c) Image at pole

(d) None

Explanation: Rays emerge parallel.

Q44. If object between center and focus of concave mirror:

(a) Image beyond center, real, inverted, magnified ✅

(b) Image at focus

(c) Image at pole

(d) None

Explanation: Produces magnified real image.

Q45. If object between focus and pole of concave mirror:

(a) Image behind mirror, virtual, erect, magnified ✅

(b) Image at infinity

(c) Image at center

(d) None

Explanation: Produces magnified virtual image.

Q46. Convex mirror focal length is considered:

(a) Positive ✅

(b) Negative

(c) Zero

(d) None

Explanation: By sign convention, convex mirror focal length is positive.

Q47. Concave mirror focal length is considered:

(a) Negative ✅

(b) Positive

(c) Zero

(d) None

Explanation: By sign convention, concave mirror focal length is negative.

Q48. If object at infinity for concave mirror:

(a) Image at focus, real, inverted, point-sized ✅

(b) Image at center

(c) Image at pole

(d) None

Explanation: Parallel rays converge at focus.

Q49. If object at infinity for convex mirror:

(a) Image at focus, virtual, erect, point-sized ✅

(b) Image at center

(c) Image at pole

(d) None

Explanation: Diverging rays appear to come from focus.

Q50. Mirror used in shaving mirrors is:

(a) Concave ✅

(b) Convex

(c) Plane

(d) None

Explanation: Concave mirror provides magnified virtual image for close objects.

Q51. Laws of refraction are known as:

(a) Snell’s law ✅

(b) Newton’s law

(c) Huygens’ principle

(d) None

Explanation: Snell’s law relates angles of incidence and refraction with refractive indices.

Q52. Snell’s law formula is:

(a) n1 sin i = n2 sin r ✅

(b) sin i = sin r

(c) tan i = tan r

(d) None

Explanation: Ratio of sines equals ratio of refractive indices.

Q53. Absolute refractive index of medium is:

(a) c/v ✅

(b) v/c

(c) c×v

(d) None

Explanation: Ratio of speed of light in vacuum to speed in medium.

Q54. Refractive index of water ≈

(a) 1.33 ✅

(b) 1.5

(c) 2.0

(d) None

Explanation: Light slows down in water compared to air.

Q55. Refractive index of glass ≈

(a) 1.5 ✅

(b) 1.33

(c) 2.0

(d) None

Explanation: Typical crown glass has n ≈ 1.5.

Q56. Apparent depth is less than real depth because:

(a) Refraction at water surface ✅

(b) Reflection

(c) Scattering

(d) None

Explanation: Light bends away from normal, making depth appear shallower.

Q57. Apparent depth formula:

(a) Real depth / refractive index ✅

(b) Real depth × refractive index

(c) Real depth − refractive index

(d) None

Explanation: Apparent depth decreases with higher refractive index.

Q58. A coin in water appears raised due to:

(a) Refraction ✅

(b) Reflection

(c) Scattering

(d) None

Explanation: Light bends at water–air interface.

Q59. Speed of light in medium is:

(a) v = c/n ✅

(b) v = cn

(c) v = c×n²

(d) None

Explanation: Higher refractive index → slower speed.

Q60. If n = 2, speed of light in medium =

(a) 1.5 × 10⁸ m/s ✅

(b) 3 × 10⁸ m/s

(c) 2 × 10⁸ m/s

(d) None

Explanation: v = c/n = 3×10⁸ / 2.

Q61. Refraction causes bending of light because:

(a) Change in speed ✅

(b) Change in amplitude

(c) Change in frequency

(d) None

Explanation: Frequency remains constant, speed changes.

Q62. Frequency of light during refraction:

(a) Remains constant ✅

(b) Increases

(c) Decreases

(d) None

Explanation: Only wavelength and speed change.

Q63. Wavelength in medium is:

(a) λ = λ0/n ✅

(b) λ = λ0×n

(c) λ = λ0+n

(d) None

Explanation: λ decreases in denser medium.

Q64. Prism deviates light due to:

(a) Refraction ✅

(b) Reflection

(c) Scattering

(d) None

Explanation: Light bends twice at prism surfaces.

Q65. Angle of minimum deviation occurs when:

(a) Angle of incidence = angle of emergence ✅

(b) Angle of incidence = 0

(c) Angle of refraction = 90°

(d) None

Explanation: Symmetry condition in prism.

Q66. Refractive index of prism formula:

(a) n = sin((A+D)/2)/sin(A/2) ✅

(b) n = sin(A)/sin(D)

(c) n = tan(A)/tan(D)

(d) None

Explanation: Derived from prism geometry.

Q67. Critical angle is defined as:

(a) Angle of incidence for 90° refraction ✅

(b) Angle of reflection

(c) Angle of deviation

(d) None

Explanation: Beyond this, total internal reflection occurs.

Q68. Critical angle formula:

(a) sin C = n2/n1 ✅

(b) sin C = n1/n2

(c) tan C = n2/n1

(d) None

Explanation: For light from denser (n1) to rarer (n2) medium.

Q69. Total internal reflection occurs when:

(a) i > C ✅

(b) i < C

(c) i = 0

(d) None

Explanation: Incident angle greater than critical angle.

Q70. Mirage is due to:

(a) Total internal reflection ✅

(b) Scattering

(c) Diffraction

(d) None

Explanation: Hot air near ground causes refraction and TIR.

Q71. Diamonds sparkle due to:

(a) Total internal reflection ✅

(b) Scattering

(c) Reflection only

(d) None

Explanation: High refractive index → small critical angle.

Q72. Optical fiber works on:

(a) Total internal reflection ✅

(b) Refraction only

(c) Scattering

(d) None

Explanation: Light guided inside fiber core.

Q73. Refractive index of air ≈

(a) 1.0003 ✅

(b) 1.0

(c) 1.33

(d) None

Explanation: Slightly greater than 1 due to density.

Q74. Apparent bending of stick in water is due to:

(a) Refraction ✅

(b) Reflection

(c) Scattering

(d) None

Explanation: Light bends at water–air interface.

Q75. Lateral shift in glass slab occurs due to:

(a) Refraction ✅

(b) Reflection

(c) Scattering

(d) None

Explanation: Parallel faces cause displacement of ray.

Q76. Critical angle is smaller for:

(a) Diamond ✅

(b) Water

(c) Glass

(d) Air

Explanation: Diamond has very high refractive index (~2.42), giving a small critical angle (~24°).

Q77. Total internal reflection is used in:

(a) Optical fibers ✅

(b) Plane mirrors

(c) Lenses

(d) None

Explanation: Light is trapped inside fiber core by repeated total internal reflection.

Q78. Mirage formation is due to:

(a) Refraction and total internal reflection ✅

(b) Scattering

(c) Diffraction

(d) None

Explanation: Hot air near ground causes bending of light rays, producing inverted images.

Q79. Sparkling of diamond is due to:

(a) Multiple total internal reflections ✅

(b) Scattering

(c) Refraction only

(d) None

Explanation: Small critical angle ensures light reflects many times inside diamond.

Q80. Endoscopy uses:

(a) Optical fibers ✅

(b) Mirrors

(c) Lenses only

(d) None

Explanation: Flexible optical fibers transmit light and images inside the body.

Q81. Optical fiber cladding has:

(a) Lower refractive index than core ✅

(b) Higher refractive index

(c) Same refractive index

(d) None

Explanation: Ensures total internal reflection at core–cladding boundary.

Q82. Lenses are made of:

(a) Transparent materials like glass/plastic ✅

(b) Metals

(c) Wood

(d) None

Explanation: Transparent medium allows refraction to form images.

Q83. Convex lens is also called:

(a) Converging lens ✅

(b) Diverging lens

(c) Plane lens

(d) None

Explanation: Convex lens bends parallel rays to meet at focus.

Q84. Concave lens is also called:

(a) Diverging lens ✅

(b) Converging lens

(c) Plane lens

(d) None

Explanation: Concave lens spreads parallel rays outward.

Q85. Lens formula is:

(a) 1/f = 1/v − 1/u ✅

(b) f = v − u

(c) f = v + u

(d) None

Explanation: Relates focal length, object distance, and image distance.

Q86. Magnification by lens is:

(a) M = v/u ✅

(b) M = u/v

(c) M = f/u

(d) None

Explanation: Ratio of image distance to object distance.

Q87. Power of lens formula:

(a) P = 100/f(cm) ✅

(b) P = f/100

(c) P = 1/f(m)

(d) None

Explanation: Power in diopters is reciprocal of focal length in meters.

Q88. Convex lens focal length is considered:

(a) Positive ✅

(b) Negative

(c) Zero

(d) None

Explanation: By sign convention, convex lens has positive focal length.

Q89. Concave lens focal length is considered:

(a) Negative ✅

(b) Positive

(c) Zero

(d) None

Explanation: By sign convention, concave lens has negative focal length.

Q90. If object at infinity for convex lens:

(a) Image at focus, real, inverted, point-sized ✅

(b) Image at center

(c) Image at pole

(d) None

Explanation: Parallel rays converge at focus.

Q91. If object at focus of convex lens:

(a) Image at infinity ✅

(b) Image at center

(c) Image at pole

(d) None

Explanation: Rays emerge parallel.

Q92. If object between focus and lens (convex):

(a) Image virtual, erect, magnified ✅

(b) Image real, inverted

(c) Image diminished

(d) None

Explanation: Produces magnified virtual image.

Q93. Concave lens always forms:

(a) Virtual, erect, diminished image ✅

(b) Real, inverted

(c) Magnified

(d) None

Explanation: Diverging rays appear to come from focus.

Q94. Convex lens used in:

(a) Magnifying glass ✅

(b) Rear-view mirror

(c) Plane mirror

(d) None

Explanation: Produces enlarged virtual image.

Q95. Concave lens used in:

(a) Spectacles for myopia ✅

(b) Spectacles for hypermetropia

(c) Telescopes

(d) None

Explanation: Diverges rays to correct short-sightedness.

Q96. Combination of lenses is used in:

(a) Optical instruments ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Multiple lenses improve magnification and image quality.

Q97. Chromatic aberration occurs because:

(a) Different colors refract differently ✅

(b) Reflection

(c) Scattering

(d) None

Explanation: Dispersion causes colored fringes in images.

Q98. Spherical aberration occurs because:

(a) Marginal rays focus differently than paraxial rays ✅

(b) Reflection

(c) Scattering

(d) None

Explanation: Causes blurred image edges.

Q99. Achromatic lens is made by:

(a) Combining convex and concave lenses ✅

(b) Using single lens

(c) Using mirrors

(d) None

Explanation: Cancels chromatic aberration.

Q100. Lens used in simple microscope is:

(a) Convex lens ✅

(b) Concave lens

(c) Plane mirror

(d) None

Explanation: Provides magnified virtual image of small objects.

Q101. The human eye acts like:

(a) A camera ✅

(b) A telescope

(c) A microscope

(d) None

Explanation: Eye has a lens system, an aperture (pupil), and a screen (retina), similar to a camera.

Q102. The transparent front part of the eye is:

(a) Cornea ✅

(b) Retina

(c) Iris

(d) None

Explanation: Cornea refracts light entering the eye.

Q103. The colored part of the eye is:

(a) Iris ✅

(b) Retina

(c) Cornea

(d) None

Explanation: Iris controls pupil size and regulates light entry.

Q104. The opening in the iris is:

(a) Pupil ✅

(b) Retina

(c) Cornea

(d) None

Explanation: Pupil acts as aperture, controlling light entering.

Q105. The lens of the eye is:

(a) Convex ✅

(b) Concave

(c) Plane

(d) None

Explanation: Eye lens converges light onto retina.

Q106. The screen of the eye is:

(a) Retina ✅

(b) Cornea

(c) Iris

(d) None

Explanation: Retina contains photoreceptor cells that detect light.

Q107. Photoreceptor cells are:

(a) Rods and cones ✅

(b) Fibers

(c) Muscles

(d) None

Explanation: Rods detect brightness, cones detect color.

Q108. The process of focusing by eye lens is:

(a) Accommodation ✅

(b) Reflection

(c) Refraction

(d) None

Explanation: Lens changes shape to focus near or distant objects.

Q109. Near point of normal eye is:

(a) 25 cm ✅

(b) 50 cm

(c) 10 cm

(d) None

Explanation: Closest distance at which eye can focus comfortably.

Q110. Far point of normal eye is:

(a) Infinity ✅

(b) 1 m

(c) 10 m

(d) None

Explanation: Eye can focus parallel rays from infinity.

Q111. Defect of eye where distant objects not seen clearly:

(a) Myopia ✅

(b) Hypermetropia

(c) Presbyopia

(d) None

Explanation: Short-sightedness corrected by concave lens.

Q112. Defect of eye where near objects not seen clearly:

(a) Hypermetropia ✅

(b) Myopia

(c) Presbyopia

(d) None

Explanation: Long-sightedness corrected by convex lens.

Q113. Age-related defect of eye is:

(a) Presbyopia ✅

(b) Myopia

(c) Hypermetropia

(d) None

Explanation: Lens loses elasticity with age.

Q114. Cataract is:

(a) Clouding of lens ✅

(b) Weakness of retina

(c) Defect of cornea

(d) None

Explanation: Cataract reduces transparency of lens.

Q115. Spectacles for myopia use:

(a) Concave lens ✅

(b) Convex lens

(c) Plane lens

(d) None

Explanation: Concave lens diverges rays to correct short-sightedness.

Q116. Spectacles for hypermetropia use:

(a) Convex lens ✅

(b) Concave lens

(c) Plane lens

(d) None

Explanation: Convex lens converges rays to correct long-sightedness.

Q117. Spectacles for presbyopia use:

(a) Bifocal lenses ✅

(b) Concave lens

(c) Convex lens

(d) None

Explanation: Bifocals correct both near and distant vision.

Q118. Optical instrument that magnifies small objects:

(a) Microscope ✅

(b) Telescope

(c) Camera

(d) None

Explanation: Microscope uses lenses to magnify tiny details.

Q119. Optical instrument that magnifies distant objects:

(a) Telescope ✅

(b) Microscope

(c) Camera

(d) None

Explanation: Telescope collects light from distant sources.

Q120. Simple microscope uses:

(a) Single convex lens ✅

(b) Concave lens

(c) Plane mirror

(d) None

Explanation: Provides magnified virtual image.

Q121. Compound microscope uses:

(a) Two convex lenses ✅

(b) Concave lenses

(c) Mirrors

(d) None

Explanation: Objective and eyepiece lenses provide high magnification.

Q122. Magnifying power of microscope depends on:

(a) Focal lengths of objective and eyepiece ✅

(b) Aperture only

(c) Lens material only

(d) None

Explanation: Shorter focal lengths give higher magnification.

Q123. Astronomical telescope uses:

(a) Objective and eyepiece lenses ✅

(b) Mirrors only

(c) Single lens

(d) None

Explanation: Collects light from distant stars and magnifies.

Q124. Magnifying power of telescope depends on:

(a) Ratio of focal lengths ✅

(b) Lens material

(c) Aperture only

(d) None

Explanation: M = fo/fe, ratio of objective to eyepiece focal length.

Q125. Spectrometer is used to:

(a) Measure refractive index and dispersion ✅

(b) Measure pressure

(c) Measure temperature

(d) None

Explanation: Spectrometer analyzes light properties using prisms or gratings.

Q126. Dispersion of light is:

(a) Splitting of white light into colors ✅

(b) Reflection

(c) Refraction only

(d) None

Explanation: Different wavelengths refract at different angles, producing a spectrum.

Q127. Dispersion occurs because:

(a) Refractive index depends on wavelength ✅

(b) Amplitude changes

(c) Frequency changes

(d) None

Explanation: Shorter wavelengths (violet) have higher refractive index than longer ones (red).

Q128. In a prism, violet light deviates:

(a) More than red ✅

(b) Less than red

(c) Same as red

(d) None

Explanation: Violet has shorter wavelength, higher refractive index, hence greater deviation.

Q129. In a prism, red light deviates:

(a) Least ✅

(b) Most

(c) Same as violet

(d) None

Explanation: Red has longer wavelength, lower refractive index.

Q130. The band of colors obtained from white light is:

(a) Spectrum ✅

(b) Rainbow

(c) Diffraction pattern

(d) None

Explanation: Spectrum consists of seven visible colors.

Q131. Order of colors in visible spectrum is:

(a) VIBGYOR ✅

(b) ROYGBIV

(c) Random

(d) None

Explanation: Violet, Indigo, Blue, Green, Yellow, Orange, Red.

Q132. Rainbow formation is due to:

(a) Refraction, reflection, dispersion ✅

(b) Scattering only

(c) Diffraction only

(d) None

Explanation: Sunlight refracts, reflects inside raindrops, and disperses into colors.

Q133. Primary rainbow is formed by:

(a) One internal reflection ✅

(b) Two internal reflections

(c) No reflection

(d) None

Explanation: Light undergoes one reflection inside raindrop.

Q134. Secondary rainbow is formed by:

(a) Two internal reflections ✅

(b) One reflection

(c) No reflection

(d) None

Explanation: Two reflections produce reversed color order.

Q135. In rainbow, red appears:

(a) Outer edge ✅

(b) Inner edge

(c) Middle

(d) None

Explanation: Red deviates least, appears outermost.

Q136. In rainbow, violet appears:

(a) Inner edge ✅

(b) Outer edge

(c) Middle

(d) None

Explanation: Violet deviates most, appears innermost.

Q137. Angle of deviation for primary rainbow is about:

(a) 42° ✅

(b) 30°

(c) 60°

(d) None

Explanation: Red light emerges at ~42° from incident sunlight.

Q138. Angle of deviation for secondary rainbow is about:

(a) 51° ✅

(b) 42°

(c) 30°

(d) None

Explanation: Secondary rainbow forms at larger angle.

Q139. Supernumerary rainbows are due to:

(a) Interference of light ✅

(b) Reflection only

(c) Refraction only

(d) None

Explanation: Overlapping waves produce faint extra bands.

Q140. Dispersion in prism causes:

(a) Angular separation of colors ✅

(b) No separation

(c) Mixing of colors

(d) None

Explanation: Different wavelengths bend differently.

Q141. Cauchy’s relation connects:

(a) Refractive index and wavelength ✅

(b) Frequency and amplitude

(c) Speed and intensity

(d) None

Explanation: n = A + B/λ², showing dispersion dependence.

Q142. White light is composed of:

(a) Seven colors ✅

(b) Three colors

(c) Infinite colors

(d) None

Explanation: Visible spectrum has seven distinct colors.

Q143. Dispersion is maximum for:

(a) Violet ✅

(b) Red

(c) Green

(d) None

Explanation: Violet bends most in prism.

Q144. Dispersion is minimum for:

(a) Red ✅

(b) Violet

(c) Blue

(d) None

Explanation: Red bends least in prism.

Q145. Rainbow is visible when:

(a) Sun is behind observer ✅

(b) Sun is overhead

(c) Sun is in front

(d) None

Explanation: Observer sees refracted light from raindrops opposite the sun.

Q146. Double rainbow shows:

(a) Reversed color order in secondary ✅

(b) Same order

(c) No order

(d) None

Explanation: Secondary rainbow has reversed colors due to two reflections.

Q147. Dispersion causes:

(a) Chromatic aberration in lenses ✅

(b) Spherical aberration

(c) Reflection

(d) None

Explanation: Different colors focus at different points.

Q148. Achromatic lens reduces:

(a) Chromatic aberration ✅

(b) Spherical aberration

(c) Diffraction

(d) None

Explanation: Combination of convex and concave lenses cancels dispersion.

Q149. Atmospheric dispersion causes:

(a) Stars to appear colored near horizon ✅

(b) Twinkling

(c) Scattering

(d) None

Explanation: Different wavelengths refract differently in atmosphere.

Q150. Rainbow is an example of:

(a) Natural dispersion ✅

(b) Artificial dispersion

(c) Reflection only

(d) None

Explanation: Sunlight disperses naturally in raindrops.

Q151. Chromatic aberration in lenses occurs because:

(a) Different colors focus at different points ✅

(b) Reflection

(c) Scattering

(d) None

Explanation: Dispersion causes each wavelength to refract differently, producing colored fringes.

Q152. Spherical aberration occurs because:

(a) Marginal rays focus differently than paraxial rays ✅

(b) Reflection

(c) Scattering

(d) None

Explanation: Rays far from axis converge at different points, blurring the image.

Q153. Astigmatism is a defect where:

(a) Eye cannot focus equally in all directions ✅

(b) Eye lens becomes opaque

(c) Retina detaches

(d) None

Explanation: Unequal curvature of cornea/lens causes distorted vision.

Q154. Achromatic lens is made by:

(a) Combining convex and concave lenses ✅

(b) Using single lens

(c) Using mirrors

(d) None

Explanation: Cancels chromatic aberration by balancing dispersion.

Q155. Reflecting telescopes use:

(a) Mirrors ✅

(b) Lenses only

(c) Prisms

(d) None

Explanation: Concave mirrors collect light, avoiding chromatic aberration.

Q156. Refracting telescopes use:

(a) Lenses ✅

(b) Mirrors

(c) Prisms

(d) None

Explanation: Objective lens collects light, eyepiece magnifies.

Q157. Binoculars use:

(a) Prisms and lenses ✅

(b) Mirrors only

(c) Single lens

(d) None

Explanation: Prisms shorten path and invert image correctly.

Q158. Camera aperture controls:

(a) Amount of light entering ✅

(b) Magnification

(c) Focal length

(d) None

Explanation: Aperture size regulates brightness and depth of field.

Q159. Camera shutter controls:

(a) Exposure time ✅

(b) Magnification

(c) Focal length

(d) None

Explanation: Shutter determines how long light falls on film/sensor.

Q160. Resolving power of optical instrument depends on:

(a) Wavelength and aperture ✅

(b) Focal length only

(c) Lens material only

(d) None

Explanation: Smaller wavelength and larger aperture improve resolution.

Q161. Diffraction limits resolution because:

(a) Light spreads when passing through aperture ✅

(b) Reflection

(c) Refraction

(d) None

Explanation: Diffraction causes overlapping of images.

Q162. Resolving power of microscope increases with:

(a) Shorter wavelength and higher numerical aperture ✅

(b) Longer wavelength

(c) Smaller aperture

(d) None

Explanation: Improves ability to distinguish fine details.

Q163. Resolving power of telescope increases with:

(a) Larger objective diameter ✅

(b) Smaller diameter

(c) Longer wavelength

(d) None

Explanation: Bigger aperture collects more light, improves resolution.

Q164. Fiber optics communication is based on:

(a) Total internal reflection ✅

(b) Refraction only

(c) Scattering

(d) None

Explanation: Light signals guided inside fiber core.

Q165. Optical fibers are immune to:

(a) Electromagnetic interference ✅

(b) Reflection

(c) Refraction

(d) None

Explanation: Signals remain secure and unaffected by external EM fields.

Q166. Optical fiber sensors measure:

(a) Strain, temperature, pressure ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Fiber sensors detect physical changes in environment.

Q167. LASER stands for:

(a) Light Amplification by Stimulated Emission of Radiation ✅

(b) Light Absorption by Stimulated Emission

(c) Light Amplification by Spontaneous Emission

(d) None

Explanation: LASER produces coherent, monochromatic light.

Q168. LASER light is:

(a) Monochromatic, coherent, directional ✅

(b) Polychromatic

(c) Incoherent

(d) None

Explanation: Unique properties make LASER useful in many applications.

Q169. LASER used in medicine for:

(a) Surgery and eye treatment ✅

(b) Cooking

(c) Heating

(d) None

Explanation: LASER precisely cuts or reshapes tissues.

Q170. LASER used in industry for:

(a) Cutting and welding ✅

(b) Cooking

(c) Heating

(d) None

Explanation: High-intensity beam melts or cuts materials.

Q171. LASER used in communication for:

(a) Optical fiber transmission ✅

(b) Radio only

(c) Sound waves

(d) None

Explanation: LASER beams carry data through fibers.

Q172. Atmospheric refraction causes:

(a) Apparent shift of star positions ✅

(b) Scattering

(c) Reflection

(d) None

Explanation: Light bends in atmosphere, altering apparent position.

Q173. Stars twinkle due to:

(a) Atmospheric refraction fluctuations ✅

(b) Reflection

(c) Scattering only

(d) None

Explanation: Turbulent air changes refractive index, causing brightness variation.

Q174. Planets do not twinkle because:

(a) They appear as extended sources ✅

(b) They are closer

(c) They are brighter

(d) None

Explanation: Extended images average out fluctuations.

Q175. Advanced optical instruments like spectrometers are used to:

(a) Analyze light properties ✅

(b) Measure mass

(c) Measure pressure

(d) None

Explanation: Spectrometers study wavelength, refractive index, and dispersion.

Q176. LASER light differs from ordinary light because it is:

(a) Monochromatic, coherent, highly directional ✅

(b) Polychromatic, incoherent

(c) Diffused

(d) None

Explanation: LASER emits a single wavelength, with waves in phase and minimal divergence.

Q177. Stimulated emission was explained by:

(a) Einstein ✅

(b) Newton

(c) Huygens

(d) Maxwell

Explanation: Einstein introduced the concept of stimulated emission in 1917, forming the basis of LASERs.

Q178. Population inversion means:

(a) More atoms in excited state than ground state ✅

(b) More atoms in ground state

(c) Equal atoms in both states

(d) None

Explanation: Essential condition for LASER action.

Q179. Optical pumping is used to:

(a) Achieve population inversion ✅

(b) Increase wavelength

(c) Reduce frequency

(d) None

Explanation: External energy excites atoms to higher states.

Q180. Ruby LASER uses:

(a) Crystalline ruby rod ✅

(b) Glass

(c) Plastic

(d) None

Explanation: Ruby crystal acts as active medium, producing red light.

Q181. He–Ne LASER emits:

(a) Red light at 632.8 nm ✅

(b) Blue light

(c) Green light

(d) None

Explanation: Helium–neon LASER is common in labs.

Q182. Semiconductor LASERs are used in:

(a) CD/DVD players ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Compact LASER diodes read optical discs.

Q183. Medical LASERs are used for:

(a) Eye surgery and tissue cutting ✅

(b) Cooking

(c) Heating

(d) None

Explanation: LASER precisely reshapes cornea or cuts tissues.

Q184. Industrial LASERs are used for:

(a) Cutting, welding, drilling ✅

(b) Cooking

(c) Heating

(d) None

Explanation: High-power LASER beams process materials.

Q185. LASER communication uses:

(a) Optical fibers ✅

(b) Radio waves

(c) Sound waves

(d) None

Explanation: LASER beams transmit data securely through fibers.

Q186. Holography uses:

(a) LASER light ✅

(b) Ordinary light

(c) Sound waves

(d) None

Explanation: Coherent LASER light records 3D images.

Q187. Hologram stores:

(a) Phase and amplitude information ✅

(b) Only amplitude

(c) Only frequency

(d) None

Explanation: Records complete wavefront, enabling 3D reconstruction.

Q188. Fiber optic cables transmit data using:

(a) Light pulses ✅

(b) Sound waves

(c) Radio waves

(d) None

Explanation: Light signals carry information at high speed.

Q189. Fiber optic cables are preferred because:

(a) High bandwidth, low loss, secure ✅

(b) Low bandwidth

(c) High loss

(d) None

Explanation: Ideal for modern communication.

Q190. Attenuation in fiber optics is due to:

(a) Scattering and absorption ✅

(b) Reflection only

(c) Refraction only

(d) None

Explanation: Imperfections reduce signal strength.

Q191. Dispersion in fiber optics causes:

(a) Pulse broadening ✅

(b) Pulse narrowing

(c) No effect

(d) None

Explanation: Different wavelengths travel at different speeds.

Q192. Single-mode fiber allows:

(a) One path of light ✅

(b) Multiple paths

(c) Random paths

(d) None

Explanation: Reduces dispersion, used for long-distance communication.

Q193. Multi-mode fiber allows:

(a) Multiple paths of light ✅

(b) Single path

(c) Random paths

(d) None

Explanation: Easier to manufacture, but more dispersion.

Q194. Fiber optic sensors detect:

(a) Strain, temperature, pressure ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Changes in light properties reveal physical conditions.

Q195. Fiber optic gyroscope measures:

(a) Rotation ✅

(b) Pressure

(c) Temperature

(d) None

Explanation: Uses interference of light to detect angular velocity.

Q196. Fiber optics in medicine are used for:

(a) Endoscopy ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Flexible fibers transmit images inside body.

Q197. Fiber optics in defense are used for:

(a) Secure communication ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Immune to electromagnetic interference.

Q198. Fiber optics in industry are used for:

(a) Monitoring machines ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Fiber sensors detect vibrations and strain.

Q199. Fiber optics in environment monitoring are used for:

(a) Detecting pollutants ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Fiber sensors measure chemical levels in air and water.

Q200. Fiber optics in aviation are used for:

(a) Aircraft communication ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Fibers transmit secure signals in aircraft systems.

Q201. Holography records:

(a) Both amplitude and phase of light ✅

(b) Only amplitude

(c) Only frequency

(d) None

Explanation: LASER light interference captures complete wavefront information, enabling 3D reconstruction.

Q202. Hologram differs from photograph because:

(a) It stores 3D information ✅

(b) It stores 2D only

(c) It uses ordinary light

(d) None

Explanation: Hologram reconstructs depth and parallax, unlike flat photographs.

Q203. Holography requires:

(a) Coherent LASER light ✅

(b) Ordinary light

(c) Sound waves

(d) None

Explanation: Coherence ensures stable interference patterns.

Q204. Applications of holography include:

(a) Data storage, security, imaging ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Holograms are used in credit cards, medical imaging, and optical storage.

Q205. Diffraction grating is used to:

(a) Separate light into wavelengths ✅

(b) Reflect light

(c) Refract light only

(d) None

Explanation: Thousands of slits produce interference patterns, dispersing light.

Q206. Resolving power of grating increases with:

(a) Number of lines per unit length ✅

(b) Fewer lines

(c) Larger wavelength

(d) None

Explanation: More slits improve angular resolution.

Q207. Interference of light occurs when:

(a) Two coherent waves overlap ✅

(b) Two incoherent waves overlap

(c) Reflection only

(d) None

Explanation: Coherent sources produce constructive and destructive interference.

Q208. Young’s double-slit experiment proved:

(a) Wave nature of light ✅

(b) Particle nature only

(c) Reflection

(d) None

Explanation: Interference fringes confirmed light behaves as a wave.

Q209. Fringe width in YDSE depends on:

(a) Wavelength, distance, slit separation ✅

(b) Amplitude only

(c) Frequency only

(d) None

Explanation: β = λD/d, where D = screen distance, d = slit separation.

Q210. Diffraction occurs when:

(a) Light bends around obstacles ✅

(b) Light reflects

(c) Light refracts

(d) None

Explanation: Wave nature causes spreading at edges.

Q211. Single-slit diffraction produces:

(a) Central bright fringe wider than others ✅

(b) Equal fringes

(c) No fringes

(d) None

Explanation: Central maximum is twice width of secondary maxima.

Q212. Polarization of light proves:

(a) Transverse nature of light ✅

(b) Longitudinal nature

(c) Particle nature

(d) None

Explanation: Only transverse waves can be polarized.

Q213. Polarizers are used to:

(a) Reduce glare ✅

(b) Increase brightness

(c) Scatter light

(d) None

Explanation: Polarized sunglasses block reflected glare.

Q214. Brewster’s law states:

(a) At certain angle, reflected light is completely polarized ✅

(b) At all angles

(c) At 90° incidence

(d) None

Explanation: Brewster angle depends on refractive index.

Q215. Brewster angle formula:

(a) tan θB = n ✅

(b) sin θB = n

(c) cos θB = n

(d) None

Explanation: θB is angle of incidence where reflection is polarized.

Q216. Malus’ law gives:

(a) Intensity of polarized light ✅

(b) Frequency

(c) Wavelength

(d) None

Explanation: I = I0 cos²θ, where θ is angle between polarizer axes.

Q217. Optical activity is:

(a) Rotation of plane of polarization ✅

(b) Reflection

(c) Refraction

(d) None

Explanation: Certain substances rotate polarization direction.

Q218. Nicol prism is used for:

(a) Producing polarized light ✅

(b) Producing scattered light

(c) Producing reflected light

(d) None

Explanation: Made of calcite, splits ordinary and extraordinary rays.

Q219. Double refraction occurs in:

(a) Birefringent crystals ✅

(b) Metals

(c) Liquids

(d) None

Explanation: Crystals like calcite split light into two rays.

Q220. Ordinary ray in birefringence obeys:

(a) Snell’s law ✅

(b) Reflection law

(c) Diffraction law

(d) None

Explanation: Ordinary ray follows normal refraction rules.

Q221. Extraordinary ray in birefringence:

(a) Does not obey Snell’s law ✅

(b) Obeys Snell’s law

(c) Reflects only

(d) None

Explanation: Its path depends on crystal orientation.

Q222. Optical rotation is measured by:

(a) Polarimeter ✅

(b) Microscope

(c) Telescope

(d) None

Explanation: Polarimeter measures rotation of plane-polarized light.

Q223. Optical activity is shown by:

(a) Quartz, sugar solutions ✅

(b) Metals

(c) Plastics

(d) None

Explanation: Certain substances rotate polarization plane.

Q224. Polarized light is used in:

(a) Stress analysis ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Polarization reveals stress patterns in transparent materials.

Q225. Polarized light is used in:

(a) 3D movies ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Different polarizations sent to each eye create 3D effect.

Q226. Polarization by reflection occurs when:

(a) Light reflects at Brewster’s angle ✅

(b) Light reflects at 90°

(c) Light reflects at 0°

(d) None

Explanation: At Brewster’s angle, reflected light is completely plane-polarized.

Q227. Polarization by scattering explains:

(a) Blue sky polarization ✅

(b) Red sunset

(c) White clouds

(d) None

Explanation: Scattered light in atmosphere is partially polarized, especially at 90° to sun.

Q228. Polarization by transmission occurs when:

(a) Light passes through polarizing material ✅

(b) Light reflects

(c) Light refracts

(d) None

Explanation: Polarizers absorb one component of vibration, transmitting only one plane.

Q229. Polarization is useful in:

(a) Sunglasses to reduce glare ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Polarized lenses block reflected light from surfaces like water or roads.

Q230. Polarization is used in:

(a) Stress analysis of transparent materials ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Polarized light reveals internal stress patterns.

Q231. Optical activity is shown by:

(a) Quartz and sugar solutions ✅

(b) Metals

(c) Plastics

(d) None

Explanation: These substances rotate plane of polarization.

Q232. Optical rotation depends on:

(a) Concentration, path length, wavelength ✅

(b) Pressure only

(c) Temperature only

(d) None

Explanation: Rotation angle increases with concentration and path length.

Q233. Polarimeter measures:

(a) Angle of optical rotation ✅

(b) Frequency

(c) Wavelength

(d) None

Explanation: Used to study optically active substances.

Q234. Circular polarization occurs when:

(a) Two perpendicular waves differ by 90° phase ✅

(b) Waves are in phase

(c) Waves are incoherent

(d) None

Explanation: Combination produces circularly rotating electric field vector.

Q235. Elliptical polarization occurs when:

(a) Two perpendicular waves differ by arbitrary phase ✅

(b) Waves are in phase

(c) Waves are incoherent

(d) None

Explanation: Produces elliptical rotation of electric field vector.

Q236. Polarized light is used in:

(a) 3D movie projection ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Different polarizations sent to each eye create depth perception.

Q237. LCD screens work using:

(a) Polarization of light ✅

(b) Reflection only

(c) Refraction only

(d) None

Explanation: Liquid crystals rotate polarization, controlling light transmission.

Q238. Optical isolators in communication use:

(a) Polarization ✅

(b) Reflection

(c) Refraction

(d) None

Explanation: Allow light to pass in one direction only, preventing feedback.

Q239. Polarization proves:

(a) Light is transverse wave ✅

(b) Light is longitudinal wave

(c) Light is particle only

(d) None

Explanation: Only transverse waves can be polarized.

Q240. Polarization is absent in:

(a) Sound waves ✅

(b) Light waves

(c) Water waves

(d) None

Explanation: Sound is longitudinal, cannot be polarized.

Q241. Double refraction occurs in:

(a) Birefringent crystals like calcite ✅

(b) Metals

(c) Liquids

(d) None

Explanation: Splits light into ordinary and extraordinary rays.

Q242. Ordinary ray obeys:

(a) Snell’s law ✅

(b) Reflection law

(c) Diffraction law

(d) None

Explanation: Ordinary ray follows normal refraction rules.

Q243. Extraordinary ray:

(a) Does not obey Snell’s law ✅

(b) Obeys Snell’s law

(c) Reflects only

(d) None

Explanation: Path depends on crystal orientation.

Q244. Nicol prism is used to:

(a) Produce polarized light ✅

(b) Produce scattered light

(c) Produce reflected light

(d) None

Explanation: Splits ordinary and extraordinary rays, transmitting one.

Q245. Optical rotation is maximum for:

(a) Shorter wavelengths ✅

(b) Longer wavelengths

(c) Equal for all

(d) None

Explanation: Rotation angle increases as wavelength decreases.

Q246. Sugar solutions are used to:

(a) Measure concentration via optical rotation ✅

(b) Measure pressure

(c) Measure temperature

(d) None

Explanation: Rotation angle proportional to concentration.

Q247. Quartz crystal shows:

(a) Strong optical activity ✅

(b) No optical activity

(c) Only refraction

(d) None

Explanation: Quartz rotates plane of polarization significantly.

Q248. Polarization is used in:

(a) Optical communication ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Polarization multiplexing increases data transmission.

Q249. Stress patterns in plastics are studied using:

(a) Polarized light ✅

(b) Ordinary light

(c) Sound waves

(d) None

Explanation: Polarization reveals internal stresses.

Q250. Optical activity is important in:

(a) Chemistry and biology ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Used to study molecular structures and concentrations.

Q251. Interference of light requires:

(a) Coherent sources ✅

(b) Incoherent sources

(c) Reflection only

(d) None

Explanation: Coherent sources have constant phase difference, essential for stable interference patterns.

Q252. Condition for constructive interference is:

(a) Path difference = nλ ✅

(b) Path difference = (2n+1)λ/2

(c) Path difference = λ/4

(d) None

Explanation: Waves add up when path difference is integral multiple of wavelength.

Q253. Condition for destructive interference is:

(a) Path difference = (2n+1)λ/2 ✅

(b) Path difference = nλ

(c) Path difference = λ

(d) None

Explanation: Waves cancel when path difference is odd multiple of half wavelength.

Q254. Young’s double-slit experiment proved:

(a) Wave nature of light ✅

(b) Particle nature only

(c) Reflection

(d) None

Explanation: Interference fringes confirmed light behaves as a wave.

Q255. Fringe width in YDSE is:

(a) β = λD/d ✅

(b) β = d/λD

(c) β = λ/d

(d) None

Explanation: Depends on wavelength, distance to screen, and slit separation.

Q256. If slit separation increases, fringe width:

(a) Decreases ✅

(b) Increases

(c) Remains same

(d) None

Explanation: β ∝ 1/d.

Q257. If wavelength increases, fringe width:

(a) Increases ✅

(b) Decreases

(c) Remains same

(d) None

Explanation: β ∝ λ.

Q258. If screen distance increases, fringe width:

(a) Increases ✅

(b) Decreases

(c) Remains same

(d) None

Explanation: β ∝ D.

Q259. Central fringe in YDSE is:

(a) Bright ✅

(b) Dark

(c) Colored

(d) None

Explanation: Path difference zero → constructive interference.

Q260. Diffraction occurs when:

(a) Light bends around obstacles ✅

(b) Light reflects

(c) Light refracts

(d) None

Explanation: Wave nature causes spreading at edges.

Q261. Single-slit diffraction produces:

(a) Central bright fringe wider than others ✅

(b) Equal fringes

(c) No fringes

(d) None

Explanation: Central maximum is twice width of secondary maxima.

Q262. Condition for minima in single-slit diffraction:

(a) a sin θ = nλ ✅

(b) a cos θ = nλ

(c) a tan θ = nλ

(d) None

Explanation: Destructive interference occurs at these angles.

Q263. Width of central maximum is:

(a) 2λD/a ✅

(b) λD/a

(c) λ/a

(d) None

Explanation: Twice the width of secondary maxima.

Q264. Diffraction grating produces:

(a) Sharp, bright spectra ✅

(b) Faint spectra

(c) No spectra

(d) None

Explanation: Thousands of slits enhance interference.

Q265. Condition for maxima in grating:

(a) d sin θ = nλ ✅

(b) d cos θ = nλ

(c) d tan θ = nλ

(d) None

Explanation: Constructive interference occurs at these angles.

Q266. Resolving power of grating increases with:

(a) Number of lines per unit length ✅

(b) Fewer lines

(c) Larger wavelength

(d) None

Explanation: More slits improve angular resolution.

Q267. Diffraction limits resolution because:

(a) Light spreads when passing through aperture ✅

(b) Reflection

(c) Refraction

(d) None

Explanation: Diffraction causes overlapping of images.

Q268. Rayleigh’s criterion defines:

(a) Minimum resolvable angle ✅

(b) Maximum angle

(c) Average angle

(d) None

Explanation: Two sources are just resolved when central maximum of one coincides with first minimum of other.

Q269. Resolving power of telescope increases with:

(a) Larger objective diameter ✅

(b) Smaller diameter

(c) Longer wavelength

(d) None

Explanation: Bigger aperture collects more light, improves resolution.

Q270. Resolving power of microscope increases with:

(a) Shorter wavelength and higher numerical aperture ✅

(b) Longer wavelength

(c) Smaller aperture

(d) None

Explanation: Improves ability to distinguish fine details.

Q271. Diffraction pattern of circular aperture shows:

(a) Airy disk ✅

(b) Bright fringes only

(c) No fringes

(d) None

Explanation: Central bright spot surrounded by rings.

Q272. Interference fringes are:

(a) Equally spaced ✅

(b) Unequally spaced

(c) Random

(d) None

Explanation: Path difference varies linearly with position.

Q273. Diffraction fringes are:

(a) Unequally spaced ✅

(b) Equally spaced

(c) Random

(d) None

Explanation: Angular width depends on sin θ relation.

Q274. Interference requires:

(a) Coherent sources ✅

(b) Incoherent sources

(c) Random sources

(d) None

Explanation: Stable phase difference is necessary.

Q275. Diffraction can occur with:

(a) Single slit, grating, aperture ✅

(b) Only double slit

(c) Only prism

(d) None

Explanation: Any obstacle or aperture comparable to wavelength produces diffraction.

Q276. Condition for maxima in double-slit interference:

(a) Path difference = nλ ✅

(b) Path difference = (2n+1)λ/2

(c) Path difference = λ/4

(d) None

Explanation: Constructive interference occurs when path difference is integral multiple of wavelength.

Q277. Condition for minima in double-slit interference:

(a) Path difference = (2n+1)λ/2 ✅

(b) Path difference = nλ

(c) Path difference = λ

(d) None

Explanation: Destructive interference occurs when path difference is odd multiple of half wavelength.

Q278. In YDSE, central fringe is:

(a) Bright ✅

(b) Dark

(c) Colored

(d) None

Explanation: Path difference zero → constructive interference.

Q279. If wavelength increases in YDSE, fringe width:

(a) Increases ✅

(b) Decreases

(c) Remains same

(d) None

Explanation: β ∝ λ.

Q280. If slit separation increases in YDSE, fringe width:

(a) Decreases ✅

(b) Increases

(c) Remains same

(d) None

Explanation: β ∝ 1/d.

Q281. If screen distance increases in YDSE, fringe width:

(a) Increases ✅

(b) Decreases

(c) Remains same

(d) None

Explanation: β ∝ D.

Q282. Diffraction grating produces:

(a) Sharp, bright spectra ✅

(b) Faint spectra

(c) No spectra

(d) None

Explanation: Thousands of slits enhance interference.

Q283. Condition for grating maxima:

(a) d sin θ = nλ ✅

(b) d cos θ = nλ

(c) d tan θ = nλ

(d) None

Explanation: Constructive interference occurs at these angles.

Q284. Resolving power of grating increases with:

(a) Number of lines per unit length ✅

(b) Fewer lines

(c) Larger wavelength

(d) None

Explanation: More slits improve angular resolution.

Q285. Diffraction pattern of circular aperture shows:

(a) Airy disk ✅

(b) Bright fringes only

(c) No fringes

(d) None

Explanation: Central bright spot surrounded by rings.

Q286. Rayleigh’s criterion defines:

(a) Minimum resolvable angle ✅

(b) Maximum angle

(c) Average angle

(d) None

Explanation: Two sources are just resolved when central maximum of one coincides with first minimum of other.

Q287. Resolving power of telescope depends on:

(a) Diameter of objective ✅

(b) Focal length only

(c) Lens material only

(d) None

Explanation: Larger aperture improves resolution.

Q288. Resolving power of microscope depends on:

(a) Wavelength and numerical aperture ✅

(b) Focal length only

(c) Lens material only

(d) None

Explanation: Shorter wavelength and larger aperture improve resolution.

Q289. Diffraction limits resolution because:

(a) Light spreads when passing through aperture ✅

(b) Reflection

(c) Refraction

(d) None

Explanation: Diffraction causes overlapping of images.

Q290. Interference fringes are:

(a) Equally spaced ✅

(b) Unequally spaced

(c) Random

(d) None

Explanation: Path difference varies linearly with position.

Q291. Diffraction fringes are:

(a) Unequally spaced ✅

(b) Equally spaced

(c) Random

(d) None

Explanation: Angular width depends on sin θ relation.

Q292. Fresnel diffraction occurs when:

(a) Source or screen is near aperture ✅

(b) Source at infinity

(c) Screen at infinity

(d) None

Explanation: Near-field diffraction produces complex patterns.

Q293. Fraunhofer diffraction occurs when:

(a) Source and screen at infinity ✅

(b) Source near aperture

(c) Screen near aperture

(d) None

Explanation: Far-field diffraction produces simple patterns.

Q294. Diffraction grating is used in:

(a) Spectroscopy ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Separates light into wavelengths for analysis.

Q295. Interference in thin films produces:

(a) Colors ✅

(b) White light only

(c) No effect

(d) None

Explanation: Path difference between reflected rays causes constructive and destructive interference.

Q296. Soap bubbles show colors due to:

(a) Thin film interference ✅

(b) Scattering only

(c) Reflection only

(d) None

Explanation: Varying thickness produces different colors.

Q297. Oil film on water shows colors due to:

(a) Thin film interference ✅

(b) Scattering only

(c) Reflection only

(d) None

Explanation: Different thicknesses cause interference of reflected light.

Q298. Newton’s rings are formed by:

(a) Interference in thin film between lens and plate ✅

(b) Diffraction

(c) Reflection only

(d) None

Explanation: Circular fringes due to varying thickness of air film.

Q299. Central spot in Newton’s rings is:

(a) Dark ✅

(b) Bright

(c) Colored

(d) None

Explanation: Path difference causes destructive interference at center.

Q300. Newton’s rings are used to:

(a) Measure wavelength of light ✅

(b) Measure pressure

(c) Measure temperature

(d) None

Explanation: Ring diameters help calculate wavelength accurately.

Q301. Newton’s rings are formed due to:

(a) Interference in thin air film ✅

(b) Diffraction

(c) Reflection only

(d) None

Explanation: Circular fringes appear between convex lens and glass plate due to varying thickness of air film.

Q302. Central spot in Newton’s rings is:

(a) Dark ✅

(b) Bright

(c) Colored

(d) None

Explanation: Path difference at center causes destructive interference.

Q303. Diameter of Newton’s rings depends on:

(a) Wavelength and radius of curvature ✅

(b) Amplitude only

(c) Frequency only

(d) None

Explanation: Ring size varies with λ and lens curvature.

Q304. Newton’s rings are used to:

(a) Measure wavelength of light ✅

(b) Measure pressure

(c) Measure temperature

(d) None

Explanation: Ring diameters help calculate wavelength accurately.

Q305. Michelson interferometer works on:

(a) Interference of light ✅

(b) Diffraction only

(c) Reflection only

(d) None

Explanation: Splits light into two paths, recombines to produce fringes.

Q306. Michelson interferometer is used to:

(a) Measure wavelength and small distances ✅

(b) Measure pressure

(c) Measure temperature

(d) None

Explanation: Extremely precise instrument for optical measurements.

Q307. Michelson interferometer was used in:

(a) Michelson–Morley experiment ✅

(b) Young’s experiment

(c) Newton’s experiment

(d) None

Explanation: Tested existence of ether, leading to relativity.

Q308. Fringe shift in Michelson interferometer indicates:

(a) Change in path length ✅

(b) Change in amplitude

(c) Change in frequency

(d) None

Explanation: Fringes move when one arm length changes.

Q309. Interference fringes in Michelson interferometer are:

(a) Circular ✅

(b) Linear

(c) Random

(d) None

Explanation: Produced by equal inclination of beams.

Q310. Fabry–Perot interferometer uses:

(a) Multiple reflections between mirrors ✅

(b) Single reflection

(c) Diffraction only

(d) None

Explanation: Produces sharp interference fringes.

Q311. Fabry–Perot interferometer is used for:

(a) High-resolution spectroscopy ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Resolves closely spaced spectral lines.

Q312. Interference filters work by:

(a) Multiple beam interference ✅

(b) Reflection only

(c) Refraction only

(d) None

Explanation: Select narrow wavelength ranges.

Q313. Thin film interference produces:

(a) Colors in soap bubbles ✅

(b) White light only

(c) No effect

(d) None

Explanation: Varying thickness causes constructive and destructive interference.

Q314. Oil film colors are due to:

(a) Thin film interference ✅

(b) Scattering only

(c) Reflection only

(d) None

Explanation: Different thicknesses cause interference of reflected light.

Q315. Condition for constructive interference in thin film:

(a) 2μt cos r = nλ ✅

(b) 2μt cos r = (2n+1)λ/2

(c) μt = λ

(d) None

Explanation: Path difference leads to bright fringes.

Q316. Condition for destructive interference in thin film:

(a) 2μt cos r = (2n+1)λ/2 ✅

(b) 2μt cos r = nλ

(c) μt = λ

(d) None

Explanation: Path difference leads to dark fringes.

Q317. Interference colors in thin films depend on:

(a) Thickness and wavelength ✅

(b) Amplitude only

(c) Frequency only

(d) None

Explanation: Different thicknesses reflect different colors.

Q318. Haidinger fringes are:

(a) Interference fringes in thin wedge-shaped films ✅

(b) Diffraction fringes

(c) Reflection fringes

(d) None

Explanation: Produced by wedge-shaped air films.

Q319. Lloyd’s mirror produces:

(a) Interference fringes ✅

(b) Diffraction fringes

(c) Reflection only

(d) None

Explanation: Interference between direct and reflected rays.

Q320. Fresnel biprism produces:

(a) Two virtual coherent sources ✅

(b) Two incoherent sources

(c) Reflection only

(d) None

Explanation: Biprism splits light into two overlapping beams.

Q321. Fresnel biprism experiment demonstrates:

(a) Interference of light ✅

(b) Diffraction only

(c) Reflection only

(d) None

Explanation: Produces interference fringes from single source.

Q322. Interference fringes shift when:

(a) Medium changes ✅

(b) Amplitude changes

(c) Frequency changes

(d) None

Explanation: Refractive index alters path difference.

Q323. Michelson interferometer can measure:

(a) Refractive index of gases ✅

(b) Pressure

(c) Temperature

(d) None

Explanation: Fringe shift reveals refractive index changes.

Q324. Fabry–Perot interferometer fringes are:

(a) Sharp and concentric ✅

(b) Broad

(c) Random

(d) None

Explanation: Multiple reflections produce high-resolution fringes.

Q325. Interference is used in:

(a) Precision measurement of wavelength ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Interference techniques provide accurate optical measurements.

Q326. Diffraction of light proves:

(a) Wave nature of light ✅

(b) Particle nature only

(c) Reflection

(d) None

Explanation: Diffraction occurs when light bends around obstacles, confirming its wave property.

Q327. Condition for single-slit diffraction minima:

(a) a sin θ = nλ ✅

(b) a cos θ = nλ

(c) a tan θ = nλ

(d) None

Explanation: Destructive interference occurs when path difference equals integer multiples of wavelength.

Q328. Width of central maximum in single-slit diffraction:

(a) 2λD/a ✅

(b) λD/a

(c) λ/a

(d) None

Explanation: Central maximum is twice as wide as secondary maxima.

Q329. Diffraction grating produces:

(a) Sharp, bright spectra ✅

(b) Faint spectra

(c) No spectra

(d) None

Explanation: Thousands of slits enhance interference, producing sharp spectral lines.

Q330. Condition for maxima in diffraction grating:

(a) d sin θ = nλ ✅

(b) d cos θ = nλ

(c) d tan θ = nλ

(d) None

Explanation: Constructive interference occurs at these angles.

Q331. Resolving power of grating increases with:

(a) Number of lines per unit length ✅

(b) Fewer lines

(c) Larger wavelength

(d) None

Explanation: More slits improve angular resolution.

Q332. Diffraction pattern of circular aperture shows:

(a) Airy disk ✅

(b) Bright fringes only

(c) No fringes

(d) None

Explanation: Central bright spot surrounded by concentric rings.

Q333. Rayleigh’s criterion defines:

(a) Minimum resolvable angle ✅

(b) Maximum angle

(c) Average angle

(d) None

Explanation: Two sources are just resolved when central maximum of one coincides with first minimum of other.

Q334. Resolving power of telescope depends on:

(a) Diameter of objective ✅

(b) Focal length only

(c) Lens material only

(d) None

Explanation: Larger aperture improves resolution.

Q335. Resolving power of microscope depends on:

(a) Wavelength and numerical aperture ✅

(b) Focal length only

(c) Lens material only

(d) None

Explanation: Shorter wavelength and larger aperture improve resolution.

Q336. Diffraction limits resolution because:

(a) Light spreads when passing through aperture ✅

(b) Reflection

(c) Refraction

(d) None

Explanation: Diffraction causes overlapping of images.

Q337. Interference fringes are:

(a) Equally spaced ✅

(b) Unequally spaced

(c) Random

(d) None

Explanation: Path difference varies linearly with position.

Q338. Diffraction fringes are:

(a) Unequally spaced ✅

(b) Equally spaced

(c) Random

(d) None

Explanation: Angular width depends on sin θ relation.

Q339. Fresnel diffraction occurs when:

(a) Source or screen is near aperture ✅

(b) Source at infinity

(c) Screen at infinity

(d) None

Explanation: Near-field diffraction produces complex patterns.

Q340. Fraunhofer diffraction occurs when:

(a) Source and screen at infinity ✅

(b) Source near aperture

(c) Screen near aperture

(d) None

Explanation: Far-field diffraction produces simple patterns.

Q341. Diffraction grating is used in:

(a) Spectroscopy ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Separates light into wavelengths for analysis.

Q342. Condition for constructive interference in thin film:

(a) 2μt cos r = nλ ✅

(b) 2μt cos r = (2n+1)λ/2

(c) μt = λ

(d) None

Explanation: Path difference leads to bright fringes.

Q343. Condition for destructive interference in thin film:

(a) 2μt cos r = (2n+1)λ/2 ✅

(b) 2μt cos r = nλ

(c) μt = λ

(d) None

Explanation: Path difference leads to dark fringes.

Q344. Interference colors in thin films depend on:

(a) Thickness and wavelength ✅

(b) Amplitude only

(c) Frequency only

(d) None

Explanation: Different thicknesses reflect different colors.

Q345. Soap bubble colors are due to:

(a) Thin film interference ✅

(b) Scattering only

(c) Reflection only

(d) None

Explanation: Varying thickness produces different colors.

Q346. Oil film colors are due to:

(a) Thin film interference ✅

(b) Scattering only

(c) Reflection only

(d) None

Explanation: Different thicknesses cause interference of reflected light.

Q347. Newton’s rings are formed by:

(a) Interference in thin film between lens and plate ✅

(b) Diffraction

(c) Reflection only

(d) None

Explanation: Circular fringes due to varying thickness of air film.

Q348. Central spot in Newton’s rings is:

(a) Dark ✅

(b) Bright

(c) Colored

(d) None

Explanation: Path difference causes destructive interference at center.

Q349. Newton’s rings are used to:

(a) Measure wavelength of light ✅

(b) Measure pressure

(c) Measure temperature

(d) None

Explanation: Ring diameters help calculate wavelength accurately.

Q350. Michelson interferometer works on:

(a) Interference of light ✅

(b) Diffraction only

(c) Reflection only

(d) None

Explanation: Splits light into two paths, recombines to produce fringes.

Q351. Michelson interferometer produces fringes due to:

(a) Superposition of two coherent beams ✅

(b) Diffraction only

(c) Reflection only

(d) None

Explanation: Light is split into two paths and recombined, producing interference fringes.

Q352. Michelson interferometer is used to:

(a) Measure wavelength and small distances ✅

(b) Measure pressure

(c) Measure temperature

(d) None

Explanation: Extremely precise instrument for optical measurements.

Q353. Michelson–Morley experiment tested:

(a) Existence of ether ✅

(b) Existence of photons

(c) Existence of electrons

(d) None

Explanation: No fringe shift observed, disproving ether theory and supporting relativity.

Q354. Fringe shift in Michelson interferometer indicates:

(a) Change in path length ✅

(b) Change in amplitude

(c) Change in frequency

(d) None

Explanation: Fringes move when one arm length changes.

Q355. Fabry–Perot interferometer uses:

(a) Multiple reflections between mirrors ✅

(b) Single reflection

(c) Diffraction only

(d) None

Explanation: Produces sharp interference fringes due to multiple beam interference.

Q356. Fabry–Perot interferometer is used for:

(a) High-resolution spectroscopy ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Resolves closely spaced spectral lines.

Q357. Interference filters work by:

(a) Multiple beam interference ✅

(b) Reflection only

(c) Refraction only

(d) None

Explanation: Select narrow wavelength ranges for transmission.

Q358. Thin film interference produces:

(a) Colors in soap bubbles ✅

(b) White light only

(c) No effect

(d) None

Explanation: Varying thickness causes constructive and destructive interference.

Q359. Oil film colors are due to:

(a) Thin film interference ✅

(b) Scattering only

(c) Reflection only

(d) None

Explanation: Different thicknesses cause interference of reflected light.

Q360. Condition for constructive interference in thin film:

(a) 2μt cos r = nλ ✅

(b) 2μt cos r = (2n+1)λ/2

(c) μt = λ

(d) None

Explanation: Path difference leads to bright fringes.

Q361. Condition for destructive interference in thin film:

(a) 2μt cos r = (2n+1)λ/2 ✅

(b) 2μt cos r = nλ

(c) μt = λ

(d) None

Explanation: Path difference leads to dark fringes.

Q362. Interference colors in thin films depend on:

(a) Thickness and wavelength ✅

(b) Amplitude only

(c) Frequency only

(d) None

Explanation: Different thicknesses reflect different colors.

Q363. Haidinger fringes are:

(a) Interference fringes in wedge-shaped films ✅

(b) Diffraction fringes

(c) Reflection fringes

(d) None

Explanation: Produced by wedge-shaped air films.

Q364. Lloyd’s mirror produces:

(a) Interference fringes ✅

(b) Diffraction fringes

(c) Reflection only

(d) None

Explanation: Interference between direct and reflected rays.

Q365. Fresnel biprism produces:

(a) Two virtual coherent sources ✅

(b) Two incoherent sources

(c) Reflection only

(d) None

Explanation: Biprism splits light into two overlapping beams.

Q366. Fresnel biprism experiment demonstrates:

(a) Interference of light ✅

(b) Diffraction only

(c) Reflection only

(d) None

Explanation: Produces interference fringes from single source.

Q367. Interference fringes shift when:

(a) Medium changes ✅

(b) Amplitude changes

(c) Frequency changes

(d) None

Explanation: Refractive index alters path difference.

Q368. Michelson interferometer can measure:

(a) Refractive index of gases ✅

(b) Pressure

(c) Temperature

(d) None

Explanation: Fringe shift reveals refractive index changes.

Q369. Fabry–Perot interferometer fringes are:

(a) Sharp and concentric ✅

(b) Broad

(c) Random

(d) None

Explanation: Multiple reflections produce high-resolution fringes.

Q370. Interference is used in:

(a) Precision measurement of wavelength ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Interference techniques provide accurate optical measurements.

Q371. Diffraction of light occurs when:

(a) Light bends around obstacles ✅

(b) Light reflects

(c) Light refracts

(d) None

Explanation: Wave nature causes spreading at edges.

Q372. Condition for single-slit diffraction minima:

(a) a sin θ = nλ ✅

(b) a cos θ = nλ

(c) a tan θ = nλ

(d) None

Explanation: Destructive interference occurs at these angles.

Q373. Width of central maximum in single-slit diffraction:

(a) 2λD/a ✅

(b) λD/a

(c) λ/a

(d) None

Explanation: Central maximum is twice as wide as secondary maxima.

Q374. Diffraction grating produces:

(a) Sharp, bright spectra ✅

(b) Faint spectra

(c) No spectra

(d) None

Explanation: Thousands of slits enhance interference.

Q375. Condition for maxima in diffraction grating:

(a) d sin θ = nλ ✅

(b) d cos θ = nλ

(c) d tan θ = nλ

(d) None

Explanation: Constructive interference occurs at these angles.

Q376. Fabry–Perot interferometer works on:

(a) Multiple beam interference ✅

(b) Single reflection

(c) Diffraction only

(d) None

Explanation: Light undergoes repeated reflections between two partially reflecting mirrors, producing sharp fringes.

Q377. Fabry–Perot interferometer is used in:

(a) High-resolution spectroscopy ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Resolves closely spaced spectral lines with great accuracy.

Q378. Interference filters select:

(a) Narrow wavelength ranges ✅

(b) Broad wavelength ranges

(c) Random wavelengths

(d) None

Explanation: Constructive interference allows only specific wavelengths to pass.

Q379. Thin film interference explains:

(a) Colors in soap bubbles ✅

(b) White light only

(c) No effect

(d) None

Explanation: Varying thickness causes constructive and destructive interference.

Q380. Oil film colors are due to:

(a) Thin film interference ✅

(b) Scattering only

(c) Reflection only

(d) None

Explanation: Different thicknesses cause interference of reflected light.

Q381. Newton’s rings are formed by:

(a) Interference in thin film between lens and plate ✅

(b) Diffraction

(c) Reflection only

(d) None

Explanation: Circular fringes due to varying thickness of air film.

Q382. Central spot in Newton’s rings is:

(a) Dark ✅

(b) Bright

(c) Colored

(d) None

Explanation: Path difference causes destructive interference at center.

Q383. Newton’s rings are used to:

(a) Measure wavelength of light ✅

(b) Measure pressure

(c) Measure temperature

(d) None

Explanation: Ring diameters help calculate wavelength accurately.

Q384. Michelson interferometer produces fringes due to:

(a) Superposition of two coherent beams ✅

(b) Diffraction only

(c) Reflection only

(d) None

Explanation: Light is split into two paths and recombined, producing interference fringes.

Q385. Michelson–Morley experiment tested:

(a) Existence of ether ✅

(b) Existence of photons

(c) Existence of electrons

(d) None

Explanation: No fringe shift observed, disproving ether theory and supporting relativity.

Q386. Fringe shift in Michelson interferometer indicates:

(a) Change in path length ✅

(b) Change in amplitude

(c) Change in frequency

(d) None

Explanation: Fringes move when one arm length changes.

Q387. Fabry–Perot interferometer fringes are:

(a) Sharp and concentric ✅

(b) Broad

(c) Random

(d) None

Explanation: Multiple reflections produce high-resolution fringes.

Q388. Interference is used in:

(a) Precision measurement of wavelength ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Interference techniques provide accurate optical measurements.

Q389. Diffraction of light occurs when:

(a) Light bends around obstacles ✅

(b) Light reflects

(c) Light refracts

(d) None

Explanation: Wave nature causes spreading at edges.

Q390. Condition for single-slit diffraction minima:

(a) a sin θ = nλ ✅

(b) a cos θ = nλ

(c) a tan θ = nλ

(d) None

Explanation: Destructive interference occurs at these angles.

Q391. Width of central maximum in single-slit diffraction:

(a) 2λD/a ✅

(b) λD/a

(c) λ/a

(d) None

Explanation: Central maximum is twice as wide as secondary maxima.

Q392. Diffraction grating produces:

(a) Sharp, bright spectra ✅

(b) Faint spectra

(c) No spectra

(d) None

Explanation: Thousands of slits enhance interference.

Q393. Condition for maxima in diffraction grating:

(a) d sin θ = nλ ✅

(b) d cos θ = nλ

(c) d tan θ = nλ

(d) None

Explanation: Constructive interference occurs at these angles.

Q394. Resolving power of grating increases with:

(a) Number of lines per unit length ✅

(b) Fewer lines

(c) Larger wavelength

(d) None

Explanation: More slits improve angular resolution.

Q395. Diffraction pattern of circular aperture shows:

(a) Airy disk ✅

(b) Bright fringes only

(c) No fringes

(d) None

Explanation: Central bright spot surrounded by concentric rings.

Q396. Rayleigh’s criterion defines:

(a) Minimum resolvable angle ✅

(b) Maximum angle

(c) Average angle

(d) None

Explanation: Two sources are just resolved when central maximum of one coincides with first minimum of other.

Q397. Resolving power of telescope depends on:

(a) Diameter of objective ✅

(b) Focal length only

(c) Lens material only

(d) None

Explanation: Larger aperture improves resolution.

Q398. Resolving power of microscope depends on:

(a) Wavelength and numerical aperture ✅

(b) Focal length only

(c) Lens material only

(d) None

Explanation: Shorter wavelength and larger aperture improve resolution.

Q399. Diffraction limits resolution because:

(a) Light spreads when passing through aperture ✅

(b) Reflection

(c) Refraction

(d) None

Explanation: Diffraction causes overlapping of images.

Q400. Modern optics applications include:

(a) LASERs, fiber optics, holography ✅

(b) Cooking

(c) Heating

(d) None

Explanation: Advanced optical technologies are widely used in communication, medicine, and industry.