# Ray Optics and Optical Instruments MCQ Class 12 Physics

Please refer to Chapter 9 Ray Optics and Optical Instruments MCQ Class 12 Physics with answers below. These multiple-choice questions have been prepared based on the latest NCERT book for Class 12 Physics. Students should refer to MCQ Questions for Class 12 Physics with Answers to score more marks in Grade 12 Physics exams. Students should read the chapter Ray Optics and Optical Instruments and then attempt the following objective questions.

## MCQ Questions Class 12 Physics Chapter 9 Ray Optics and Optical Instruments

The Ray Optics and Optical Instruments MCQ Class 12 Physics provided below covers all important topics given in this chapter. These MCQs will help you to properly prepare for exams.

Question. For a total internal reflection, which of the following is correct?
(a) Light travels from rarer to denser medium.
(b) Light travels from denser to rarer medium.
(c) Light travels in air only.
(d) Light travels in water only.

B

Question. Which of-the following is not a property of light?
(a) It can travel through vacuum
(b) It has a finite speed
(c) It requires a material medium for its propagation
(d) It involve transportation energy

C

Question. A convex lens is dipped in a liquid whose refractive index is equal to the refractive index of the lens. Then its focal length will
(a) become zero
(b) become infinite
(c) become small, but non-zero
(d) remain unchanged

B

Question. Ashort p ulse of white light is incident from air to a glass slab atnormal incidence. After travelling through the slab, the first colour to emerge is
(a) blue.
(b) green.
(c) violet.
(d) red.

D

Question. Which of the following phenomena is used in optical fibres ?
(a) Total internal reflection
(b) Scattering
(c) Diffraction
(d) Refraction

A

Question. The combination of which of the following processes results in the formation of a rainbow?
(a) Dispersion and Total Internal Reflection
(b) Dispersion and Absorption
(c) Refraction and Scattering
(d) Dispersion and Focussing

A

Question. Which of the following causes refraction of light?
(a) Change in the density of light from one medium to another
(b) Change in viscosity of light from one medium to another
(c) Change in the speed of light from one medium to another
(d) Change in direction of light from one medium to another

C

Question. Which of the following cannot be polarised?
(b) transverse waves
(c) sound waves
(d) X-rays

C

Question. A concave mirror is held in water. What should be the change in the focal length of the mirror?
(a) Halved
(b) Doubled
(c) Remains the same
(d) Increases exponentially

C

Question. An under-water swimmer cannot see very clearly even in absolutely clear water because of
(a) absorption of light in water
(b) scattering of light in water
(c) reduction of speed of light in water
(d) change in the focal length of eye lens

D

Question. A prism has an angle 600 and refractive index √2, what is the angle of minimum deviation?
(a) 900
(b) 600
(c) 450
(d) 300

D

Question. Identify the factor on which the angle of deviation of the prism does not depend.
(a) The angle of incidence
(b) The material of the prism
(c) The angle of reflection
(d) The wavelength of light used

C

Question. The unit of power of a lens is
(a) lambda
(b) candela
(c) diopter
(d) watt

C

Question. An astronomical refractive telescope has an objective of focal length 20 m and an eyepiece of focal length 2 cm. Then
(a) the magnification is 1000
(b) the length of the telescope tube is 20.02 m
(c) the image formed of inverted
(d) all of these

D

Question. A convergent lens will become less convergent in :
(a) oil
(b) water
(c) both of (a) and (b)
(d) none of these

B

Question. Mirage is a phenomenon due to
(a) refraction of light
(b) reflection of light
(c) total internal reflection of light
(d) diffraction of light.

C

Question. Ray Optics is also known as ____________ optics.
(a) physical
(b) polar
(c) geometrical
(d) rectilinear

C

Question. To increase the angular magnification of a simple microscope, one should increase
(a) the focal length of the lens
(b) the power of the lens
(c) the aperture of the lens
(d) the object size

B

Question. If the power of a lens is +1D, its focal length will be
(a) 1 meter
(b) 0,5 meter
(c) 2 meter
(d) 1.5 meter

A

Question. The air bubble inside water shine due to:
(a) Reflection
(b) Refraction
(c) T.l.R.
(d) None of these

C

Question. The phenomena involved in the reflection of radio waves by ionosphere is similar to
(a) reflection of light by a plane mirror.
(b) total internal reflection of light in air during a mirage.
(c) dispersion of light by water molecules during the formation of a rainbow.
(d) scattering of light by the particles of air.

B

Question. When the angle of incidence of a light ray is greater than the critical angle it gets
(a) critically refracted
(b) totally reflected
(c) total internally reflected
(d) totally refracted

C

Question. The visible light consists of waves with wavelengths ranging from-
(a) 4000 Å to 7000 Å
(b) 4500 Å to 7000 Å
(c) 4000 Å to 6500 Å
(d) 4500 Å to 6000 Å

A

Question. Critical angle of light passing from glass to water is minimum for
(a) red colour
(b) green colour
(c) yellow colour
(d) violet colour

D

Question. The optical fibre works on the principle of
(a) Scattering
(b) Refraction
(c) Dispersion
(d) Total internal reflection

D

Question. Which of the following colour of white light deviated most when passes through a prism?
(a) Red light
(b) Violet light
(c) Yellow light
(d) Both (i) and (ii)

B

Question. The field of view is maximum for
(a) plane mirror
(b) concave mirror
(c) convex mirror
(d) cylindrical mirror

C

Question. Which of the following phenomena is used in optical fibres ?
(a) Total internal reflection
(b) Scattering
(c) Diffraction
(d) Refraction

A

Question. A virtual image larger than the object can be obtained by
(a) concave mirror
(b) convex mirror
(c) plane mirror
(d) concave lens

A

Question. An object is placed 40 cm from a concave mirror of focal length 20 cm. The image formed is
(a) real, inverted and same in size
(b) real, inverted and smaller
(c) virtual, erect and larger
(d) virtual, erect and smaller

A

Question. Which of the following causes dispersion?
(a) Refraction
(b) Reflection
(c) Total internal reflection
(d) Total internal dispersion

A

Question. The image formed by objective lens of a compound Microscope is :
(a) Virtual and diminished
(b) Real and diminished
(c) Real and large
(d) Virtual and Large

C

Question. For which of the following pairs is the critical angle the smallest :
(a) Water-air
(b) Glass-water
(c) Glass-air
(d) Glass-Glass

C

Question. A passenger in an aeroplane shall
(a) never see a rainbow.
(b) may see a primary and a secondary rainbow as concentric circles.
(c) may see a primary and a secondary rainbow as concentric arcs.
(d) shall never see a secondary rainbow.

B

Question. Which of the following phenomena taken place when a monochromatic light is incident on a prism ?
(a) Dispersion
(b) Deviation
(c) Interference
(d) All of the above

B

Question. A spherical mirror is immersed in water, its focal length will
(a) Increase
(b) Decrease
(c) Remain constant
(d) None of these

C

Question. Which colour of light has a shortest wavelength ?
(a) red
(b) yellow
(c) blue
(d) violet

D

Question. A convergent lens will become less convergent in :
(a) oil
(b) water
(c) both of (a) and (b)
(d) none of these

B

(a) always real
(b) always virtual
(c) certainly real if the object is virtual
(d) certainly virtual if the object is real

C

Question. A passenger in an aeroplane shall
(a) never see a rainbow.
(b) may see a primary and a secondary rainbow as concentric circles.
(c) may see a primary and a secondary rainbow as concentric arcs.
(d) shall never see a secondary rainbow.

B

Question. Which of the following phenomena taken place when a monochromatic light is incident on a prism ?
(a) Dispersion
(b) Deviation
(c) Interference
(d) All of the above

B

Question. A spherical mirror is immersed in water, its focal length will
(a) Increase
(b) Decrease
(c) Remain constant
(d) None of these

C

Question. Which colour of light has a shortest wavelength ?
(a) red
(b) yellow
(c) blue
(d) violet

D

Question. A convergent lens will become less convergent in :
(a) oil
(b) water
(c) both of (a) and (b)
(d) none of these

B

Question. The maximum and minimum distance between a convex lens and an object, for the magnification of a real image to be greater than one are
(a) 2f and f
(b) f and zero
(c) ¥ and 2f
(d) 4f and 2f

A

Question. The focal lengths of objective and eye lens of an astronomical telelscope are respectively 2 meter and 5 cm. Final image is formed at
(i) least distance of distinct vision
(ii) infinity Magnifying power in two cases will be

(a) – 48, – 40
(b) – 40, – 48
(c) – 40, + 48
(d) – 48, + 40

A

Question. A double convex lens of focal length 6 cm is made of glass of refractive index 1.5. The radius of curvature of one surface is double that of other surface. The value of small radius of curvature is
(a) 6 cm
(b) 4.5 cm
(c) 9 cm
(d) 4 cm

B

Question. A prism has a refracting angle of 60º. When placed in the position of minimum deviation, it produces a deviation of 30º. The angle of incidence is
(a) 30º
(b) 45º
(c) 15º
(d) 60º

B

Question. A ray of light passes through an equilateral prism such that the angle of incidence is equal to the angle of emergence and the latter is equal to 3/4th of the angle of prism. The angle of deviation is
(a) 45º
(b) 39º
(c) 20º
(d) 30º

D

Question. We wish to see inside an atom. Assume the atom to have a diameter of 100 pm. This means that one must be able to resolve a width of say 10 pm. If an electron microscope is used the energy required should be
(a) 1.5 keV
(b) 50 keV
(c) 150 keV
(d) 1.5 MeV

B

Question. A plane convex lens of focal length 16 cm, is to be made of glass of refractive index 1.5. The radius of curvature of the curved surface should be
(a) 8 cm
(b) 12 cm
(c) 16 cm
(d) 24 cm

A

Question. The frequency of a light wave in a material is 2 × 1014 Hz and wavelength is 5000 Å. The refractive index of material will be
(a) 1.50
(b) 3.00
(c) 1.33
(d) 1.40

B

Question. The wavelength of a monochromatic light in vacuum is l. It travels from vacuum to a medium of absolute refractive index μ. The ratio of wavelength of the incident and refracted wave is
(a) μ2 : 1
(b) 1 : 1
(c) μ : 1
(d) 1 : μ

C

Question. Why is refractive index in a transparent medium greater than one ?
(a) Because the speed of light in vaccum is always less than speed in a transparent medium
(b) Because the speed of light in vaccum is always greater than speed in a transparent medium
(c) Frequency of wave changes when it crosses medium
(d) None of these

B

Question. Two thin lenses are in contact and the focal length of the combination is 80 cm. If the focal length of one lens is 20 cm, then the power of the other lens will be
(a) 1.66 D
(b) 4.00 D
(c) – 100 D
(d) – 3.75 D

D

Question. The refractive indices of glass and water with respect to air are 3/2 and 4/3 respectively. Then the refractive index of glass with respect to water is
(a) 8/9
(b) 9/8
(c) 7/6
(d) 2