HOTs Ray Optics and Optical Instruments Class 12 Physics

Please refer to Ray Optics and Optical Instruments HOTs Class 12 Physics provided below with Ray Optics and Optical Instruments. All HOTs for Class 12 Physics with answers provided below have been designed as per the latest syllabus and examination petter issued by CBSE, NCERT, KVS. Students of Standard 12 Physics should learn the solved HOTS for Class 12 Physics provided below to gain better marks in examinations.

Ray Optics and Optical Instruments Class 12 Physics HOTs

Assertion (A) & Reason(R)

Instructions:
Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
a) Both A and R are true and R is the correct explanation of A
b) Both A and R are true but R is NOT the correct explanation of A
c) A is true but R is false
d) A is false and R is also false

Question. Assertion : The air bubble shines in water.
Reason : Air bubble in water shines due to refraction of light

Question. Assertion : The stars twinkle while the planets do not.
Reason : The stars are much bigger in size than the planets. Correct

Question. Assertion : The colour of the green flower seen through red glass appears to be dark.
Reason : Red glass transmits only red light.

Question. Assertion : A double convex lens (μm = 1.5) has focal length 10 cm. When the lens is immersed in water (μl = 4/3) its focal length becomes 40 cm.
Reason : 1/f = [(μl−μm)/μm](1/R1−1/R2) Correct

Question. Assertion : Within a glass slab, a double convex air bubble is formed. This air bubble behaves like a converging lens.
Reason : Refractive index of air is more than the refractive index of glass. Correct

Question. Assertion : The size of the mirror affect the nature of the image.
Reason : Small mirrors always forms a virtual image.

Question. Assertion : There is no dispersion of light refracted through a rectangular glass slab.
Reason : Dispersion of light is the phenomenon of splitting of a beam of white light into its constituent
colours.

Question. Assertion : A beam of white light gives a spectrum on passing through a hollow prism.
Reason : Speed of light outside the prism is different from the speed of light inside the prism.

Question. Assertion : The focal length of lens does not change when red light is replaced by blue light.
Reason : The focal length of lens does not depends on colour of light used. Correct.

Case based Questions

1) Total internal reflection.

Question. What is refractive index of a medium(in terms of speed of light)
a) Speed of light in medium/speed of light in vacuum
b) Speed of light in vacuum/speed of light in medium
c) Speed of light in medium speed of light in vacuum
d) None of the above.

Question. In the above diagram, calculate the speed of light in the liquid of unknown refractive index.
a) 1.2 × 10⁸ m/𝑠
b) 1.4 × 10⁸ m/𝑠
c) 1.6 × 10⁸ m/𝑠
d) 1.8 × 10⁸ m/𝑠

Question. What is refractive index of a medium(in terms of real and apparent depth).
a) Real depth/ App depth
b) App/ Real depth
c) App Real depth
d) Real + App depth

Question. What is the relation between refractive index and critical angle for a medium.
a) n = 1/sin ic
b) n = sin ic
c) 1 = n/ sin ic
d) None of the above

2) Advance sunrise and delayed sunset

Question. What is the principal behind Advance sunrise and delayed sunset.
(a) Reflection.
(b) Refraction.
c) Dispersion
d) Total internal reflection.

Question. For how much time the sun is visible apparently after sunset.
(a) Approx. 5 minutes
b) Approx. 10 minutes
c) Approx. 2 minutes
d) None of the above

Question. The Sun looks reddish while sunset or sunrise, because.
a) red colour is highly scattered.
b) red colour is least scattered.
c) of refraction of light.
d) of dispersion of light.

Question. The above given phenomenon cannot be observed on the moon because
a) total internal reflection could not take place on the moon
b) there is no atmosphere
c) Sun is not visible from the moon
d) None of the above

3) Optical fibres: Now-a-days optical fibres are extensively used for transmitting audio and video
signals through long distances. Optical fibres too make use of the phenomenon of total internal
reflection. Optical fibres are fabricated with high quality composite glass/quartz fibres. Each fibre
consists of a core and cladding. The refractive index of the material of the core is higher than that
of the cladding. When a signal in the form of light is directed at one end of the fibre at a suitable
angle, it undergoes repeated total internal reflections along the length of the fibre and finally comes out at the other end. Since light undergoes total internal reflection at each stage, there is no appreciable loss in the intensity of the light signal. Optical fibres are fabricated such that light reflected at one side of inner surface strikes the other at an angle larger than the critical angle. Even if the fibre is bent, light can easily travel along its length. Thus, an optical fibre can be used to act as an optical pipe.

Question. Which of the following statement is not true.
a) Optical fibres is based on the principle of total internal reflection.
b) The refractive index of the material of the core is less than that of the cladding.
c) an optical fibre can be used to act as an optical pipe.
d) there is no appreciable loss in the intensity of the light signal while propagating through an
optical fibre.

Question. What is the condition for total internal reflection to occur?
a) angle of incidence must be equal to the critical angle.
b) angle of incidence must be less than the critical angle.
c) angle of incidence must be greater than the critical angle.
d) None of the above.

Question. Which of the following is not an application of total internal reflection?
a) Mirage
b) Sparkling of diamond
c) Splitting of white light through a prism.
d) Totally reflecting prism.

Question. Optical fibres are used extensively to transmit
a) Optical Signal
b) current
c) Sound waves
d) None of the above