{"id":12448,"date":"2025-09-16T06:08:35","date_gmt":"2025-09-16T05:08:35","guid":{"rendered":"https:\/\/mcqsadda.com\/?p=12448"},"modified":"2025-10-22T09:31:22","modified_gmt":"2025-10-22T08:31:22","slug":"light-top-100-mcqs-with-answer-and-explanation","status":"publish","type":"post","link":"https:\/\/mcqsadda.com\/index.php\/2025\/09\/16\/light-top-100-mcqs-with-answer-and-explanation\/","title":{"rendered":"Light Top 100 MCQs With Answer and Explanation"},"content":{"rendered":"\n

1<\/strong>.A<\/strong><\/mark> light\u2011year is a measure of:<\/mark><\/strong>
A) Speed
B) Distance
C) Time
D) Velocity
Answer:<\/strong> B) Distance
Explanation:<\/strong> A light\u2011year is the distance that light travels in vacuum in one Julian year (~365.25 days). It is not a measure of time or speed.<\/p>\n\n\n\n

2. Which portion of the electromagnetic spectrum can be perceived by the human eye?<\/strong><\/mark>
A) Between 400 nm and 700 nm
B) Between 40 nm and 70 nm
C) Between 400 nm and 7000 nm
D) Between 4 nm and 700 nm
Answer:<\/strong> A) Between 400 nm and 700 nm
Explanation:<\/strong> Visible light ranges approximately from 400\u2011700 nanometres; wavelengths shorter than ~400 nm are ultraviolet, longer than ~700 nm are infrared.<\/p>\n\n\n\n

3.When white light passes through a prism, which of the following happens to the light ray of shortest wavelength?<\/mark><\/strong>
A) Accelerated and refracted the most
B) Slowed down and refracted the most
C) Accelerated and refracted the least
D) Slowed down and refracted the least
Answer:<\/strong> B) Slowed down and refracted the most
Explanation:<\/strong> In dispersive media, shorter wavelength light (e.g., violet) slows down more relative to vacuum (higher refractive index) and bends more (higher refraction) than longer wavelengths.<\/p>\n\n\n\n

4.In a plane mirror:<\/mark><\/strong>
A) The image formed is real and inverted
B) The image is virtual, erect, same size as object
C) The focal length is finite (non\u2011infinite)
D) It converges parallel rays of light
Answer:<\/strong> B) The image is virtual, erect, same size as object
Explanation:<\/strong> Plane mirrors form virtual images (you cannot project them on screen), erect (upright) and the image appears as far behind the mirror as the object is in front, of same size. The focal length of a plane mirror is effectively infinite; it does not converge parallel rays.<\/p>\n\n\n\n

5.What is the focal length of a concave lens with power \u22125 D?<\/mark><\/strong>
A) \u22125\u202fm
B) \u22125\u202fcm
C) \u221220\u202fcm
D) \u22120.2\u202fm
Answer:<\/strong> D) \u22120.2\u202fm
Explanation:<\/strong> Power (in metres) so . Negative for concave lens.<\/p>\n\n\n\n

6.Which phenomenon is responsible for the blue color of the daytime sky?<\/mark><\/strong>
A) Absorption
B) Scattering
C) Reflection
D) Refraction
Answer:<\/strong> B) Scattering
Explanation:<\/strong> Rayleigh scattering of sunlight by molecules in the atmosphere scatters shorter wavelengths (blue) more strongly, so sky appears blue.<\/p>\n\n\n\n

7.Total internal reflection occurs when light travels from:<\/mark><\/strong>
A) A rarer to a denser medium
B) A denser to a rarer medium at angle greater than critical angle
C) Vacuum to any medium
D) Medium with lower refractive index into one with higher refractive index
Answer:<\/strong> B) A denser to a rarer medium at angle greater than critical angle
Explanation:<\/strong> Total internal reflection happens only when going from optically denser medium to a less dense medium, and when angle of incidence exceeds the critical angle.<\/p>\n\n\n\n

8.A concave mirror produces a virtual, erect, magnified image. Where must the object be placed?<\/mark><\/strong>
A) At the centre of curvature
B) Between the centre of curvature and the focus
C) Between focus and the pole of the mirror
D) At infinity
Answer:<\/strong> C) Between focus and the pole of the mirror
Explanation:<\/strong> When object is between focal point (F) and the mirror\u2019s surface (pole), concave mirror gives virtual, erect, magnified image. If object farther, image becomes real etc.<\/p>\n\n\n\n

9.What kind of lens is used in movie projectors (to project large image on screen)?<\/mark><\/strong>
A) Concave lens
B) Convex lens
C) Meniscus lens
D) Cylindrical lens
Answer:<\/strong> B) Convex lens
Explanation:<\/strong> Convex (converging) lens is used to project light to form image on screen; the lens brings diverging rays to converge onto screen forming real image.<\/p>\n\n\n\n

10.If all colors of white light are reflected by a surface, the surface appears:<\/mark><\/strong>
A) Black
B) White
C) Grey
D) Opaque
Answer:<\/strong> B) White
Explanation:<\/strong> White light is sum of all visible colors. If none are absorbed, all are reflected, making it appear white. Black means none reflected (all absorbed).<\/p>\n\n\n\n

11.The magnifying power of a telescope can be increased by:<\/mark><\/strong>
A) Decreasing the focal length of the eyepiece
B) Increasing the diameter of the objective
C) Reducing the focal length of the objective
D) Increasing the diameter of the eyepiece
Answer:<\/strong> A) Decreasing the focal length of the eyepiece
Explanation:<\/strong> Angular magnification \u2248 focal length of objective \/ focal length of eyepiece. Smaller eyepiece focal length \u2192 higher magnification. Increasing objective diameter improves light gathering (brightness, resolution) but doesn\u2019t directly increase magnification.<\/p>\n\n\n\n

12.Which of these waves cannot be polarized?<\/mark><\/strong>
A) Light waves
B) Water surface waves
C) Longitudinal sound waves
D) Electromagnetic waves
Answer:<\/strong> C) Longitudinal sound waves
Explanation:<\/strong> Polarization refers to orientation of oscillations in transverse waves. Longitudinal waves oscillate in direction of propagation, so cannot be polarized.<\/p>\n\n\n\n

13.What is the appearance of the sky to an observer on the Moon during lunar day?<\/mark><\/strong>
A) Blue
B) Black
C) Light yellow
D) Orange
Answer:<\/strong> B) Black
Explanation:<\/strong> The Moon has virtually no atmosphere, so there is no scattering of sunlight; thus the sky remains black even when the surface is lit by Sun.<\/p>\n\n\n\n

1<\/strong><\/mark>4.Which eye defect causes image focus in front of the retina?<\/mark><\/strong>
A) Myopia
B) Hyperopia
C) Astigmatism
D) Presbyopia
Answer:<\/strong> A) Myopia
Explanation:<\/strong> In myopia (nearsightedness), the eyeball is too long or focal length too short, so parallel rays focus before the retina. Hyperopia is opposite: focus behind retina.<\/p>\n\n\n\n

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  1. <\/li>\n<\/ol>\n\n\n\n

    15.The refractive index of a medium is . Which relation between angle of incidence and refraction is correct?<\/mark><\/strong>
    A)
    B)
    C)
    D)
    Answer:<\/strong> A)
    Explanation:<\/strong> By Snell\u2019s law, . So .<\/p>\n\n\n\n

    16.How far must an object be placed in front of a convex lens of focal length 20 cm so that the image formed is diminished (smaller than the object)?<\/mark><\/strong>
    A) 10 cm
    B) At infinity
    C) Just beyond 2F (i.e., > 40 cm)
    D) Between F and 2F
    Answer:<\/strong> C) Just beyond 2F (i.e., > 40 cm)
    Explanation:<\/strong> For a convex lens: if object is beyond 2F, image is real, inverted, diminished (smaller). Between F and 2F image is magnified; at 2F same size; at infinity highly diminished.<\/p>\n\n\n\n

    17.We see lightning before hearing thunder because:<\/mark><\/strong>
    Answer:<\/strong> D) Both A & C
    Explanation:<\/strong> Light travels extremely fast (\u2248 3\u00d710\u2078 m\/s) while sound in air is much slower (~343 m\/s), so we see light first. Also, sound\u2019s slower travel contributes.<\/p>\n\n\n\n

    18.Which of the following statements about the eye is correct?<\/mark><\/strong>
    A) The image formed on retina is virtual and erect
    B) The image is real and inverted
    C) The eye lens is concave in shape
    D) Eye defect treated by convex lens is myopia
    Answer:<\/strong> B) The image is real and inverted
    Explanation:<\/strong> The lens of the eye is convex; it forms a real, inverted, diminished image on the retina, which brain interprets as erect. Myopia is treated by concave lens; hyperopia by convex.<\/p>\n\n\n\n

    19.If the power of a lens is \u22122\u202fD, what is its focal length?<\/mark><\/strong>
    A) \u22120.5 m
    B) \u22121 m
    C) +0.5 m
    D) +1 m
    Answer:<\/strong> A) \u22120.5 m
    Explanation:<\/strong> (in metres). So m. Negative indicates diverging (concave) lens.<\/p>\n\n\n\n

    20.Which phenomenon causes golden shine seen in some sea shells?<\/mark><\/strong>
    A) Diffraction
    B) Dispersion
    C) Polarization
    D) Reflection
    Answer:<\/strong> C) Polarization
    Explanation:<\/strong> The golden shine (iridescence) in shells often arises from tiny layers (microstructure) that cause interference and selective polarization; the polarized light reflections make some colors more intense. (Some sources may attribute interference + reflection; but commonly polarization plays a role in color effects due to microstructure.)<\/p>\n\n\n\n

    21.A beam of white light is incident on a glass prism. Which color emerges deviated the least?<\/mark><\/strong>
    A) Violet
    B) Blue
    C) Red
    D) Green
    Answer:<\/strong> C) Red
    Explanation:<\/strong> Red light has the longest wavelength in visible spectrum and is refracted the least (lower dispersion), so least deviation.<\/p>\n\n\n\n

    22.If the refractive index of medium A w.r.t medium B is 1.5, then the refractive index of B w.r.t A is:<\/mark><\/strong>
    A) 1.5
    B) 2\/3
    C) \u221a(1.5)
    D) (1.5)\u00b2
    Answer:<\/strong> B) 2\/3
    Explanation:<\/strong> <\/p>\n\n\n\n

    23.A convex mirror always forms:<\/mark><\/strong>
    A) A real, inverted image
    B) A virtual, erect image
    C) A virtual, inverted image
    D) A real, erect image
    Answer:<\/strong> B) A virtual, erect image
    Explanation:<\/strong> Convex mirrors diverge rays; image is always virtual (behind mirror), erect (upright), and smaller than object.<\/p>\n\n\n\n

    24.The critical angle for water\u2011air interface is ~48\u00b0. If light inside water strikes the surface at 60\u00b0, what happens?<\/mark><\/strong>
    A) Refraction into air
    B) Total internal reflection
    C) Partial reflection and partial refraction
    D) Absorption
    Answer:<\/strong> B) Total internal reflection
    Explanation:<\/strong> Angle of incidence > critical angle yields total internal reflection.<\/p>\n\n\n\n

    25.In Young\u2019s double slit experiment: fringe width is directly proportional to:<\/mark><\/strong>
    A) slit separation
    B) wavelength
    C) distance between slits and screen
    D) both B and C
    Answer:<\/strong> D) both B and C
    Explanation:<\/strong> Fringe width . So increases with wavelength (\u03bb) and distance to screen (D), inversely with slit separation (d).<\/p>\n\n\n\n

    26.A lens has focal length 15 cm. If an object is placed at 30 cm, the image distance (for a convex lens) is:<\/mark><\/strong>
    A) 30 cm
    B) 15 cm
    C) 10 cm
    D) 20 cm
    Answer:<\/strong> D) 20 cm
    Explanation:<\/strong> Using lens formula: . Here f=15 cm, u = \u221230 cm \u2192 . So v = 30 cm. Actually wait, sign conventions: if object at 30\u202fcm, image distance comes out positive 30\u202fcm. But that suggests answer A. But if using standard object distance = +30, get v = 30. But common convention uses u negative so v positive. So correct answer: A) 30\u202fcm<\/strong>.<\/p>\n\n\n\n

     27.If a convex lens is dipped in a medium having the same refractive index as the lens material, its focal length becomes:<\/mark><\/strong>
    A) 0
    B) Infinite
    C) Very small non\u2011zero
    D) Unchanged
    Answer:<\/strong> B) Infinite
    Explanation:<\/strong> When lens and surrounding medium have same refractive index, lens has no bending power; behaves as if focal length infinite.<\/p>\n\n\n\n

    28.Which of these colors has the shortest wavelength in visible spectrum?<\/mark><\/strong>
    A) Green
    B) Red
    C) Violet
    D) Yellow
    Answer:<\/strong> C) Violet
    Explanation:<\/strong> Violet \u2248 400\u202fnm (short end), then blue, green, yellow, red.<\/p>\n\n\n\n

    29.An object at infinity is observed by eye. Where is the image formed?<\/mark><\/strong>
    A) On the retina
    B) Behind the retina
    C) In front of the retina
    D) Does not form an image
    Answer:<\/strong> A) On the retina
    Explanation:<\/strong> For relaxed eye, rays from infinity are focused on the retina.<\/p>\n\n\n\n

    30.The power of accommodation in human eye refers to:<\/mark><\/strong>
    A) Ability to see far objects
    B) Ability to adjust lens focal length to see objects at different distances
    C) Ability to focus only at a fixed distance
    D) Power of eye lens only
    Answer:<\/strong> B) Ability to adjust lens focal length to see objects at different distances
    Explanation:<\/strong> Accommodation is ciliary muscles adjusting the focal length so seen objects at various distances.<\/p>\n\n\n\n

    31.Which optical instrument uses two convex lenses to magnify distant objects?<\/mark><\/strong>
    A) Microscope
    B) Telescope
    C) Magnifying glass
    D) Spectrometer
    Answer:<\/strong> B) Telescope
    Explanation:<\/strong> Refracting telescope uses objective convex lens + eyepiece to magnify distant objects.<\/p>\n\n\n\n

    32.If for a convex lens, object is placed at 2F (twice focal length), then image will be:<\/mark><\/strong>
    A) At F
    B) At 2F
    C) Between F and 2F
    D) At infinity
    Answer:<\/strong> B) At 2F
    Explanation:<\/strong> Object at 2F produces image of equal size at 2F on other side.<\/p>\n\n\n\n

    33.In diffraction of light through a single slit, as slit width decreases, the central maximum becomes:<\/mark><\/strong>
    A) Narrower and brighter
    B) Wider and dimmer
    C) Wider and brighter
    D) Narrower and dimmer
    Answer:<\/strong> B) Wider and dimmer
    Explanation:<\/strong> Narrower slit \u2192 more diffraction \u2192 central maximum spreads (wider), amplitude falls \u2192 dimmer.<\/p>\n\n\n\n

    34.Polarization of light can occur by:<\/mark><\/strong>
    A) Reflection
    B) Refraction
    C) Scattering
    D) All of the above
    Answer:<\/strong> D) All of the above
    Explanation:<\/strong> Light becomes polarized by reflection at certain angles (Brewster\u2019s law), by scattering, and selective absorption etc.<\/p>\n\n\n\n

    35.Which is NOT true about Huygens\u2019 principle?<\/mark><\/strong>
    A) Every point on a wavefront acts as source of secondary wavelets
    B) Wavefront is envelope of secondary wavelets
    C) Works for reflection and refraction
    D) Wavelets always spherical in shape
    Answer:<\/strong> D) Wavelets always spherical in shape
    Explanation:<\/strong> In general medium, wavelets are spherical; but if medium is anisotropic or in certain geometries, shape may differ. Also some interpretations say \u201calways\u201d spherical is too restrictive.<\/p>\n\n\n\n

    36.The resolving power of microscope increases if:<\/mark><\/strong>
    A) Wavelength of illumination increases
    B) Numerical aperture decreases
    C) Numerical aperture increases
    D) Eyepiece focal length increases
    Answer:<\/strong> C) Numerical aperture increases
    Explanation:<\/strong> Resolving power \u221d NA \/ \u03bb. Higher NA gives better resolution; shorter \u03bb also helps.<\/p>\n\n\n\n

    37.A light ray passes from air into water (n\u22481.33). What happens to its speed, wavelength, and frequency?<\/mark><\/strong>
    A) Speed and wavelength decrease; frequency remains same
    B) Speed increases; wavelength decreases; frequency changes
    C) Speed decreases; wavelength increases; frequency remains same
    D) All three change
    Answer:<\/strong> A) Speed and wavelength decrease; frequency remains same
    Explanation:<\/strong> Frequency is an invariant when crossing boundary; speed in medium = c \/ n; wavelength = (speed)\/frequency \u2192 lower.<\/p>\n\n\n\n

    38.Which phenomenon is used in \u201cmirage\u201d formation?<\/mark><\/strong>
    A) Total internal reflection
    B) Refraction due to gradient of air density
    C) Reflection from ground
    D) Diffraction
    Answer:<\/strong> B) Refraction due to gradient of air density
    Explanation:<\/strong> Mirage is caused by refractive index changing with height (air temperature gradient), bending light rays; in some cases total internal reflection happens at surface of hot ground.<\/p>\n\n\n\n

    39.The focal length of a combination of two thin lenses in contact is given by:<\/mark><\/strong>
    A) f\u2081 + f\u2082
    B) (f\u2081 + f\u2082) \/ (f\u2081 f\u2082)
    C) (f\u2081 f\u2082) \/ (f\u2081 + f\u2082)
    D) f\u2081 f\u2082
    Answer:<\/strong> C) (f\u2081 f\u2082) \/ (f\u2081 + f\u2082)
    Explanation:<\/strong> Lens formula for thin lenses in contact: \u2192 f = (f\u2081f\u2082)\/(f\u2081 + f\u2082)<\/p>\n\n\n\n

    40.If the power of a lens is +4 diopters, its focal length is:<\/mark><\/strong>
    A) +0.25\u202fm
    B) +4\u202fm
    C) \u22120.25\u202fm
    D) +0.04\u202fm
    Answer:<\/strong> A) +0.25\u202fm
    Explanation:<\/strong> Power P = 1\/f (in metres) \u2192 f = 1\/4 = 0.25 m.<\/p>\n\n\n\n

    41.Which optical phenomenon explains the colorful rings seen around a street lamp through a foggy or misty atmosphere?<\/mark><\/strong>
    A) Diffraction
    B) Dispersion
    C) Polarization
    D) Total internal reflection
    Answer:<\/strong> A) Diffraction
    Explanation:<\/strong> Fine particles cause diffraction of light and interference, forming rings around light sources in mist\/fog.<\/p>\n\n\n\n

    42.Which of the following is a coherent source of light?<\/mark><\/strong>
    A) Two different lamps
    B) Laser
    C) Light from sun and moon
    D) Reflected light from wall
    Answer:<\/strong> B) Laser
    Explanation:<\/strong> Coherent light has constant phase difference and same frequency; laser is a good example.<\/p>\n\n\n\n

    43.In a refraction experiment, if angle of incidence in air is 30\u00b0 and refractive index of glass is 1.5, what is angle of refraction?<\/mark><\/strong>
    (use Snell\u2019s law)
    A) ~19.5\u00b0
    B) ~20\u00b0
    C) ~45\u00b0
    D) ~30\u00b0
    Answer:<\/strong> A) ~19.5\u00b0
    Explanation:<\/strong> . Here 1\u00d7sin30\u00b0 = 1.5 \u00d7 sin \u03b8\u2082 \u2192 sin \u03b8\u2082 = (0.5)\/(1.5) \u22480.333 \u2192 \u03b8\u2082 \u224819.5\u00b0.<\/p>\n\n\n\n

    44.The phenomenon of splitting of white light into its constituent colours is called:<\/mark><\/strong>
    A) Dispersion
    B) Diffraction
    C) Polarization
    D) Scattering
    Answer:<\/strong> A) Dispersion
    Explanation:<\/strong> Dispersion = dependence of refractive index on wavelength, causing different bending.<\/p>\n\n\n\n

    45.Which one of these is NOT a requirement for producing interference patterns?<\/mark><\/strong>
    A) Coherent sources
    B) Monochromatic light
    C) Small slit sizes comparable to wavelength
    D) Thick screen
    Answer:<\/strong> D) Thick screen
    Explanation:<\/strong> Thickness of screen is irrelevant; what matters are coherence, monochromaticity, slit and separation conditions.<\/p>\n\n\n\n

    46.In which case will the image formed by a concave mirror be enlarged?<\/mark><\/strong>
    A) Object beyond centre of curvature
    B) Object at centre of curvature
    C) Object between focus and centre of curvature
    D) Object at focus
    Answer:<\/strong> C) Object between focus and centre of curvature
    Explanation:<\/strong> For concave mirror, object between F and C \u2192 image real, inverted, enlarged. If at C, image same size; beyond C, diminished.<\/p>\n\n\n\n

    47.A ray of light inside a medium strikes boundary at the critical angle. What angle does the refracted ray make with the boundary?<\/mark><\/strong>
    A) 90\u00b0
    B) 0\u00b0
    C) Equal to critical angle
    D) Depends on medium
    Answer:<\/strong> A) 90\u00b0
    Explanation:<\/strong> At critical angle, refracted ray grazes along boundary, i.e., at 90\u00b0 to normal.<\/p>\n\n\n\n

    48.What is the effect on diffraction pattern of single slit when wavelength increases?<\/mark><\/strong>
    A) More fringes appear, central maxima narrower
    B) Central maxima becomes wider, fringes more separated
    C) Pattern disappears
    D) No change
    Answer:<\/strong> B) Central maxima becomes wider, fringes more separated
    Explanation:<\/strong> Diffraction width \u221d \u03bb, so increasing \u03bb spreads pattern.<\/p>\n\n\n\n

    49.Which of the following is a longitudinal wave?<\/mark><\/strong>
    A) Light wave
    B) Sound wave
    C) Water surface wave
    D) Electromagnetic wave
    Answer:<\/strong> B) Sound wave
    Explanation:<\/strong> Longitudinal: oscillations parallel to direction of propagation; sound in air is one.<\/p>\n\n\n\n

    50.The image formed by convex lens for object at focal point is:<\/mark><\/strong>
    A) At infinity
    B) At object itself
    C) Between lens and focal point
    D) Virtual and erect
    Answer:<\/strong> A) At infinity
    Explanation:<\/strong> When object placed at focal point, light rays exit parallel and image forms at infinity.<\/p>\n\n\n\n

    51.What h<\/strong><\/mark>appens to the refracted light when it passes from medium with lower optical density to higher optical density?<\/mark><\/strong>
    A) It bends away from normal
    B) It bends towards normal
    C) It continues straight
    D) Total internal reflection occurs
    Answer:<\/strong> B) It bends towards normal
    Explanation:<\/strong> When going into denser medium (higher refractive index), light slows and bends towards normal.<\/p>\n\n\n\n

    52.An optical fibre uses which phenomenon to transmit light along its length?<\/mark><\/strong>
    A) Refraction
    B) Diffraction
    C) Total internal reflection
    D) Polarization
    Answer:<\/strong> C) Total internal reflection
    Explanation:<\/strong> Light is totally internally reflected within the fibre if incidence angles are above critical, allowing transmission with little loss.<\/p>\n\n\n\n

    53.The sky appears reddish during sunrise and sunset because:<\/mark><\/strong>
    A) Dispersion
    B) Scattering of longer wavelengths
    C) Scattering of shorter wavelengths
    D) Absorption of shorter wavelengths
    Answer:<\/strong> C) Scattering of shorter wavelengths
    Explanation:<\/strong> At sunrise\/sunset, sunlight passes through thicker atmosphere: blue\/violet scattered out, leaving red\/orange. So the scattering of shorter (blue) removes those colours; longer wavelengths dominate.<\/p>\n\n\n\n

    54.Which of the following will give maximum resolving power for telescope?<\/mark><\/strong>
    A) Small objective diameter, small focal length
    B) Large objective diameter
    C) Eyepiece focal length large
    D) Eyepiece focal length small
    Answer:<\/strong> B) Large objective diameter
    Explanation:<\/strong> Resolving power for telescope ~ (objective diameter) \/ wavelength. Bigger diameter \u2192 higher resolution.<\/p>\n\n\n\n

    55.In Young\u2019s double slit experiment, if one of the slits is covered partially (transmits only half intensity), the interference pattern’s contrast (visibility) will:<\/mark><\/strong>
    A) Increase
    B) Decrease
    C) Remain same
    D) Disappear
    Answer:<\/strong> B) Decrease
    Explanation:<\/strong> Visibility = (I_max \u2212 I_min)\/(I_max + I_min). If amplitudes differ, I_min increases \u2192 contrast lowers.<\/p>\n\n\n\n

    56.Mirror whose surface is curved inward is called:<\/mark><\/strong>
    A) Convex mirror
    B) Concave mirror
    C) Plane mirror
    D) Spherical mirror
    Answer:<\/strong> B) Concave mirror
    Explanation:<\/strong> \u201cCurved inward\u201d means the reflecting surface curves inward (like inside of a bowl) \u2014 concave.<\/p>\n\n\n\n

    57.Which statement is true for light traveling in vacuum?<\/mark><\/strong>
    A) It travels slower than in glass
    B) Its speed depends on wavelength
    C) Its speed is constant (c) for all wavelengths
    D) Its frequency changes upon entering a medium
    Answer:<\/strong> C) Its speed is constant (c) for all wavelengths
    Explanation:<\/strong> In vacuum, light speed is constant (~3\u00d710\u2078 m\/s) independent of wavelength; frequency remains constant when entering a medium.<\/p>\n\n\n\n

    58.If an object placed between focus (F) and mirror\/pole of a concave mirror, the image is:<\/mark><\/strong>
    A) Real, inverted
    B) Virtual, erect
    C) At infinity
    D) Diminished
    Answer:<\/strong> B) Virtual, erect
    Explanation:<\/strong> For concave mirror, object between F and pole gives virtual, upright, magnified image.<\/p>\n\n\n\n

    59.Which of these optical devices reduce aberration in lenses?<\/mark><\/strong>
    A) Using thicker lenses
    B) Using combination of lens types (achromatic doublet)
    C) Using single thin convex lens only
    D) Increasing aperture
    Answer:<\/strong> B) Using combination of lens types (achromatic doublet)
    Explanation:<\/strong> Achromatic doublets combine convex + concave lenses of different glass to reduce chromatic aberration.<\/p>\n\n\n\n

    60.If the slit separation in Young\u2019s experiment is doubled, fringe width will:<\/mark><\/strong>
    A) Double
    B) Halve
    C) Remain same
    D) Increase by factor \u221a2
    Answer:<\/strong> B) Halve
    Explanation:<\/strong> Fringe width . If d doubles, \u03b2 halves (D, \u03bb constant).<\/p>\n\n\n\n

    61.A beam of unpolarized light falls on a glass surface at Brewster\u2019s angle. The reflected light is:<\/mark><\/strong>
    A) Unpolarized
    B) Completely polarized parallel to surface
    C) Completely polarized perpendicular to surface
    D) Partially polarized
    Answer:<\/strong> B) Completely polarized parallel to surface
    Explanation:<\/strong> At Brewster\u2019s angle, reflected ray is fully polarized with electric vector perpendicular to the plane of incidence (i.e., parallel to surface).<\/p>\n\n\n\n

    62.<\/mark><\/strong>
    A) Virtual and erect
    B) Real and inverted
    C) At infinity
    D) No image
    Answer:<\/strong> A) Virtual and erect
    Explanation:<\/strong> Object inside focus (10 < 15) \u2192 image virtual, upright, enlarged behind mirror.<\/p>\n\n\n\n

    63.Which of the following phenomena requires light to behave like a wave?<\/mark><\/strong>
    A) Photoelectric effect
    B) Compton scattering
    C) Diffraction
    D) Photo-luminescence
    Answer:<\/strong> C) Diffraction
    Explanation:<\/strong> Diffraction, interference require wave nature. Photoelectric & Compton show particle nature.<\/p>\n\n\n\n

    64.When light passes from air into glass, which of the following changes?<\/mark><\/strong>
    A) Speed of light decreases
    B) Frequency decreases
    C) Wavelength increases
    D) Frequency increases
    Answer:<\/strong> A) Speed of light decreases
    Explanation:<\/strong> Speed decreases; frequency remains same; wavelength decreases.<\/p>\n\n\n\n

    65.The apparent depth of a pool of water is 2 m. The real depth is 2.5 m. The refractive index of water relative to air is:<\/mark><\/strong>
    A) 1.25
    B) 0.8
    C) 1.5
    D) 1.2
    Answer:<\/strong> C) 1.25 or similar? Actually apparent depth \/ real depth = 2 \/ 2.5 = 0.8 \u2192 refractive index = real\/apparent = 2.5 \/ 2 = 1.25.
    So Answer:<\/strong> A) 1.25
    Explanation:<\/strong> Refractive index = real depth \/ apparent depth.<\/p>\n\n\n\n

    66.A person 6\u202fft tall wishes to see his whole image in a plane mirror. The mirror must be at least what height and where placed?<\/mark><\/strong>
    A) Height half his height, anywhere in room
    B) Half his height, lower edge at waist level
    C) Full height, lower edge on floor
    D) Half height, placed such that top of mirror is halfway between his eyes and top of head
    Answer:<\/strong> A) Half his height, anywhere in front (lower edge at some appropriate height)
    Explanation:<\/strong> A plane mirror of half the object height is sufficient to see whole body, since rays from feet & head reflect appropriately.<\/p>\n\n\n\n

    67.Which of these statements about electromagnetic spectrum is correct?<\/mark><\/strong>
    A) Gamma rays have longer wavelengths than radio waves
    B) Visible light has shorter wavelength than ultraviolet
    C) Infrared has longer wavelength than visible light
    D) Microwave has shorter wavelength than ultraviolet
    Answer:<\/strong> C) Infrared has longer wavelength than visible light
    Explanation:<\/strong> Ordering wavelength from small to large: gamma < X < UV < visible < infrared < microwaves < radio.<\/p>\n\n\n\n

    68.In the photoelectric effect, if intensity of incident light doubles (wavelength unchanged), which happens?<\/mark><\/strong>
    A) Number of photoelectrons increases
    B) Kinetic energy of photoelectrons increases
    C) Threshold frequency changes
    D) Both B & C
    Answer:<\/strong> A) Number of photoelectrons increases
    Explanation:<\/strong> Intensity \u2191 gives more photons per unit time \u2192 more electrons emitted. KE per photoelectron depends on photon energy (wavelength), not intensity.<\/p>\n\n\n\n

    69.Which among the following is TRUE regarding a concave lens?<\/mark><\/strong>
    A) Always forms real image
    B) Same as convex mirror
    C) Diverging lens: always virtual image
    D) Converging effect
    Answer:<\/strong> C) Diverging lens: always virtual image
    Explanation:<\/strong> Concave lens diverges light, gives virtual, erect, diminished image no matter object position.<\/p>\n\n\n\n

    70.If a convex mirror is used, as object moves further away, the image formed:<\/mark><\/strong>
    A) Moves closer to mirror pole
    B) Moves further back behind mirror
    C) Size increases
    D) Becomes real
    Answer:<\/strong> A) Moves closer to mirror pole
    Explanation:<\/strong> For convex mirror, image distance (virtual) decreases in magnitude (image moves closer to mirror) as object distance increases; size decreases.<\/p>\n\n\n\n

    71.The phenomenon responsible for \u201ctwinkling of stars\u201d is:<\/mark><\/strong>
    A) Reflection
    B) Refraction
    C) Diffraction
    D) Scattering
    Answer:<\/strong> B) Refraction
    Explanation:<\/strong> Twinkling caused by atmospheric refraction; variations in refractive index cause the star\u2019s image to shift and vary in brightness.<\/p>\n\n\n\n

    72.Which of these optical paths has maximum time of travel for light?<\/mark><\/strong>
    A) Straight line path in vacuum
    B) Slightly curved path in medium of high refractive index
    C) Longer path in lower refractive index
    D) Same path but making zig\u2011zag
    Answer:<\/strong> B) Slightly curved path in medium of high refractive index
    Explanation:<\/strong> Time = path length \u00d7 (n \/ c). High n slows light; so even if path short, a medium with high refractive index can take more time.<\/p>\n\n\n\n

    73.The resolving power of a grating is given by:<\/mark><\/strong>
    A) N*m (number of slits \u00d7 order)
    B) (\u03bb \/ d)
    C) (d \/ \u03bb)
    D) (1 \/ number of slits)
    Answer:<\/strong> A) N*m
    Explanation:<\/strong> Resolving power R = N * m, where N = number of slits illuminated, m = diffraction order.<\/p>\n\n\n\n

    74.Colour of thin oil film seen is from constructive interference. If thickness of film increases gradually, observed colour will shift toward:<\/mark><\/strong>
    A) Red end (longer \u03bb)
    B) Blue end (shorter \u03bb)
    C) Violet only
    D) No shift
    Answer:<\/strong> A) Red end (longer \u03bb)
    Explanation:<\/strong> With larger path difference, constructive interference happens for larger wavelengths \u2192 colour shifts toward red.<\/p>\n\n\n\n

    75.Light from two coherent sources superpose. If their phase difference is \u03c0, then at that point intensity is:<\/mark><\/strong>
    A) Maximum
    B) Minimum (zero)
    C) Half of maximum
    D) Dependent on amplitudes
    Answer:<\/strong> B) Minimum (zero)
    Explanation:<\/strong> Phase difference \u03c0 (180\u00b0) \u2192 destructive interference if amplitudes equal \u2192 zero intensity.<\/p>\n\n\n\n

    76.In a rainbow, primary rainbow\u2019s angular radius is about:<\/mark><\/strong>
    A) 30\u00b0
    B) 42\u00b0
    C) 50\u00b0
    D) 90\u00b0
    Answer:<\/strong> B) 42\u00b0
    Explanation:<\/strong> Primary rainbow radius ~42\u00b0 for red; inner violet around ~40\u00b0.<\/p>\n\n\n\n

    77.Which of these instruments uses a combination of lenses so one lens corrects chromatic aberration of another?<\/mark><\/strong>
    A) Simple magnifier
    B) Achromatic telescope (uses achromatic lenses)
    C) Concave mirror telescope
    D) Pinhole camera
    Answer:<\/strong> B) Achromatic telescope
    Explanation:<\/strong> Achromatic doublet uses two lens elements made from glasses with different dispersion to reduce chromatic aberration.<\/p>\n\n\n\n

    78.A prism only disperses light when its refractive index depends on:<\/mark><\/strong>
    A) Temperature
    B) Wavelength
    C) Pressure
    D) Angle
    Answer:<\/strong> B) Wavelength
    Explanation:<\/strong> Dispersion arises because refractive index varies with wavelength.<\/p>\n\n\n\n

    79.Which factor does not affect speed of light in a medium?<\/mark><\/strong>
    A) Refractive index of medium
    B) Wavelength of light (in medium)
    C) Temperature of medium (if it changes refractive index)
    D) Intensity of light
    Answer:<\/strong> D) Intensity of light
    Explanation:<\/strong> Speed depends on medium\u2019s properties (n), possibly temperature etc, but not on light\u2019s intensity.<\/p>\n\n\n\n

    80.Which of the following is true about virtual images?<\/mark><\/strong>
    A) Can be projected on a screen
    B) Formed by converging rays
    C) Formed when diverging rays appear to come from a point
    D) Always inverted
    Answer:<\/strong> C) Formed when diverging rays appear to come from a point
    Explanation:<\/strong> Virtual images are where light doesn\u2019t actually converge, but appears to diverge from a point behind or within device. They are erect typically; can\u2019t project them.<\/p>\n\n\n\n

    81.Light behaves like waves according to which theory?<\/mark><\/strong>
    A) Newton\u2019s corpuscular theory
    B) Huygens\u2019 wave theory
    C) Bohr\u2019s atomic model
    D) Einstein\u2019s photoelectric effect
    Answer:<\/strong> B) Huygens\u2019 wave theory
    Explanation:<\/strong> Huygens described light propagation via wavefronts and secondary wavelets.<\/p>\n\n\n\n

    82. If monochromatic light of wavelength 600 nm is used in Young\u2019s double slit with slit separation 0.5 mm and screen distance 1 m, the fringe width is:<\/mark><\/strong>
    A) 1.2 mm
    B) 1.0 mm
    C) 0.6 mm
    D) 0.5 mm
    Answer:<\/strong> A) 1.2 mm
    Explanation:<\/strong> \u03b2 = (\u03bb D)\/d = (600\u00d710\u207b\u2079 * 1) \/ (0.5\u00d710\u207b3) = (600\u00d710\u207b\u2079)\/(5\u00d710\u207b4) = 1.2\u00d710\u207b3 m = 1.2 mm.<\/p>\n\n\n\n

    83.Which of the following statements about mirrors is false?<\/mark><\/strong>
    A) In a plane mirror, image distance = object distance
    B) Convex mirror always gives erect image
    C) Concave mirror always gives virtual image
    D) Mirror line of symmetry is the principal axis
    Answer:<\/strong> C) Concave mirror always gives virtual image
    Explanation:<\/strong> False: A concave mirror can give real images if object is outside focal length; only when object is inside focal length it gives virtual image.<\/p>\n\n\n\n

    84.The angle between refracted and reflected ray when light hits glass at 0\u00b0 incidence is:<\/mark><\/strong>
    A) 0\u00b0
    B) 90\u00b0
    C) 180\u00b0
    D) Depends on refractive index
    Answer:<\/strong> A) 0\u00b0
    Explanation:<\/strong> At normal incidence, light goes straight into the medium (refracted ray continues normal), reflected ray is back along same path \u2014 the angle between them is 0\u00b0 or 180\u00b0 depending convention, but essentially no deviation.<\/p>\n\n\n\n

    85.Light is incident at the Brewster angle on a glass slab. Which of these is true?<\/mark><\/strong>
    A) Reflected and refracted rays are at right angles
    B) Reflected ray is parallel to refracted ray
    C) Reflected light is unpolarized
    D) Refracted light is absent
    Answer:<\/strong> A) Reflected and refracted rays are at right angles
    Explanation:<\/strong> At Brewster\u2019s angle, reflected and refracted rays are perpendicular.<\/p>\n\n\n\n

    86.Which of the following is NOT a type of aberration in lenses\/mirrors?<\/mark><\/strong>
    A) Spherical aberration
    B) Chromatic aberration
    C) Comatic aberration
    D) Geometric aberration
    Answer:<\/strong> D) Geometric aberration
    Explanation:<\/strong> Common aberrations: spherical, chromatic, coma (comatic), astigmatism etc. \u201cGeometric aberration\u201d is generic and not standard type by that name.<\/p>\n\n\n\n

    87.If image formed by a convex lens is same size as object, then object is placed at:<\/mark><\/strong>
    A) Focal point
    B) Centre of curvature (2F)
    C) Between F and 2F
    D) Beyond 2F
    Answer:<\/strong> B) Centre of curvature (2F)
    Explanation:<\/strong> Object at 2F gives image at 2F same size.<\/p>\n\n\n\n

    88.In a prism, angle of minimum deviation depends on:<\/mark><\/strong>
    A) Wavelength of light
    B) Refractive index
    C) Apex angle of prism
    D) All above
    Answer:<\/strong> D) All above
    Explanation:<\/strong> Minimum deviation depends on wavelength (since refractive index depends on it), prism\u2019s apex angle, and refractive index.<\/p>\n\n\n\n

    89.What is the image produced by a concave mirror when object is at infinity?<\/mark><\/strong>
    A) At F, real, inverted, very small
    B) At C, real, inverted
    C) Virtual, erect at infinity
    D) No image
    Answer:<\/strong> A) At F, real, inverted, very small
    Explanation:<\/strong> Rays parallel to principal axis converge at focal point; image is very small (point) at F.<\/p>\n\n\n\n

    90.Which of these optical phenomena cannot be explained by geometrical optics?<\/mark><\/strong>
    A) Reflection
    B) Refraction
    C) Interference
    D) Formation of images by lenses
    Answer:<\/strong> C) Interference
    Explanation:<\/strong> Interference arises from wave nature; geometrical optics treats light as rays and cannot explain interference, diffraction, polarization fully.<\/p>\n\n\n\n

    91.The principle that light takes path of least time through two points is called:<\/mark><\/strong>
    A) Fermat\u2019s principle
    B) Huygens\u2019 principle
    C) Snell\u2019s law
    D) Law of reflection
    Answer:<\/strong> A) Fermat\u2019s principle
    Explanation:<\/strong> Fermat\u2019s principle: light travels between two points in such a way that the travel time is minimal (or stationary).<\/p>\n\n\n\n

    92.In double slit, if path difference is 2.5 \u03bb, what is phase difference?<\/mark><\/strong>
    A) 2.5 \u03c0
    B) 5 \u03c0
    C) \u03c0\/2
    D) 5\u03c0\/2
    Answer:<\/strong> D) 5\u03c0\/2
    Explanation:<\/strong> Phase difference = (2\u03c0 \/ \u03bb) \u00d7 path difference = (2\u03c0\/\u03bb) * (2.5 \u03bb) = 5\u03c0.<\/p>\n\n\n\n

    93.Which type of mirror is used in car rear\u2011view mirrors (wide angle)?<\/mark><\/strong>
    A) Plane mirror
    B) Convex mirror
    C) Concave mirror
    D) Parabolic mirror
    Answer:<\/strong> B) Convex mirror
    Explanation:<\/strong> Convex mirror gives erect, diminished image and wide field of view.<\/p>\n\n\n\n

    94.What happens to the image when an object approaches a concave mirror from outside 2F to F?<\/mark><\/strong>
    A) Image moves between F and C and gets larger
    B) Image stays fixed
    C) Image moves towards infinity
    D) Image becomes virtual
    Answer:<\/strong> A) Image moves between F and C and gets larger
    Explanation:<\/strong> As object moves from 2F toward F, image forms beyond 2F to beyond C and magnifies.<\/p>\n\n\n\n

    95.The photoelectric effect demonstrates which property of light?<\/mark><\/strong>
    A) Wave nature
    B) Particle nature
    C) Both wave and particle nature
    D) Neither
    Answer:<\/strong> B) Particle nature
    Explanation:<\/strong> Photoelectric effect shows quantization: light photons, threshold frequency etc.<\/p>\n\n\n\n

    96.If slit separation in Young\u2019s experiment is 1 mm, screen distance D = 2 m, wavelength = 500 nm, what is separation between 2nd and 3rd bright fringe?<\/mark><\/strong>
    A) (2 * \u03bbD)\/d
    B) (3 * \u03bbD)\/d
    C) ( (3\u22122) * \u03bbD )\/d = \u03bbD\/d
    Which numerically = (1 \u00d7 10\u207b6 * 2) \/ (1 \u00d7 10\u207b3) = 2 \u00d7 10\u207b3 m = 2 mm
    So Answer:<\/strong> ~2 mm<\/p>\n\n\n\n

    97.Which of the following devices uses interference to produce coloured patterns?<\/mark><\/strong>
    A) Pinhole camera
    B) Soap film
    C) Convex mirror
    D) Concave lens
    Answer:<\/strong> B) Soap film
    Explanation:<\/strong> Thin films produce interference between reflections from two surfaces \u2192 coloured fringes.<\/p>\n\n\n\n

    98.If a light ray in glass (n=1.5) hits boundary with air at angle 50\u00b0, will total internal reflection occur?<\/mark><\/strong>
    A) Yes, since critical angle ~41\u00b0
    B) No, since angle < critical angle
    C) Yes, since angle > critical angle
    D) Cannot say
    Answer:<\/strong> C) Yes, since angle > critical angle
    Explanation:<\/strong> Critical angle for glass\u2013air \u2248 arcsin(1\/1.5) \u224841\u00b0. 50\u00b0 > 41\u00b0 \u2192 total internal reflection.<\/p>\n\n\n\n

    99.Which phenomenon is exploited in the operation of a focusing telescope?<\/strong><\/mark>
    A) Refraction only
    B) Reflection only
    C) Reflection + refraction
    D) Diffraction
    Answer:<\/strong> C) Reflection + refraction
    Explanation:<\/strong> Many telescopes use mirrors (reflection) or combination with lenses (refraction). For refracting telescopes, refraction; for reflecting telescopes, reflection; many modern use both in designs.<\/p>\n\n\n\n

    100.If a monochromatic light source is placed at the centre of a hollow glass sphere in air, what will observer see?<\/mark><\/strong>
    A) No light
    B) Light beam refracted out
    C) Light from all directions due to reflection inside glass
    D) Light escapes at various points by refraction
    Answer:<\/strong> D) Light escapes at various points by refraction
    Explanation:<\/strong> Rays inside the sphere will undergo refraction at the glass\u2011air interface depending on incidence angle; many rays exit, though internal reflections may also occur depending on geometry.<\/p>\n","protected":false},"excerpt":{"rendered":"

    1.A light\u2011year is a measure of:A) SpeedB) DistanceC) TimeD) VelocityAnswer: B) DistanceExplanation: A light\u2011year is the distance that light travels in vacuum in one Julian year (~365.25 days). It is not a measure of time or speed. 2. Which portion of the electromagnetic spectrum can be perceived by the human eye?A) Between 400 nm and<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[15543,15481,15549,15546,15547,15545,15548,15551,15553,15558,15541,15465,15542,15550,15552,15536,15479,15474,15467,15483,15472,15456,15554,15478,15544,15557,15469,15555,15480,15556],"class_list":{"0":"post-12448","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-physics","7":"tag-color-of-light","8":"tag-competitive-exam-physics","9":"tag-dispersion-of-light","10":"tag-human-eye","11":"tag-image-formation","12":"tag-laws-of-reflection","13":"tag-laws-of-refraction","14":"tag-lenses-and-mirrors","15":"tag-light-concepts","16":"tag-light-experiments","17":"tag-light-in-physics","18":"tag-mcqs-for-physics-exam","19":"tag-nature-of-light","20":"tag-optical-instruments","21":"tag-optics","22":"tag-physics-formulas","23":"tag-physics-learning","24":"tag-physics-mcqs","25":"tag-physics-preparation-material","26":"tag-physics-questions-and-answers","27":"tag-physics-quiz","28":"tag-physics-study-material","29":"tag-prism-and-spectrum","30":"tag-psc-physics-mcqs","31":"tag-reflection-of-light","32":"tag-refraction-of-light","33":"tag-ssc-physics-mcqs","34":"tag-total-internal-reflection","35":"tag-upsc-physics-mcqs","36":"tag-wave-optics"},"_links":{"self":[{"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/posts\/12448","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/comments?post=12448"}],"version-history":[{"count":6,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/posts\/12448\/revisions"}],"predecessor-version":[{"id":15044,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/posts\/12448\/revisions\/15044"}],"wp:attachment":[{"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/media?parent=12448"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/categories?post=12448"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/tags?post=12448"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}