Q 1 – Study the following ray diagram :
In this Diagram the angle of incidence the angle of emergence and the angle of deviationires pectiyely have been represented by.
(A) y, p and z
(B) x, p and z
(C) p, y and z
(D) p, z and y
Ans. option (C ) is correct .
Q 2 – Which of the following phenomena of light are involved in the formation of a rainbow?
(A) Reflection, refraction and dispersion
(B) Refraction, dispersion and total internal reflection
(C) Refraction, dispersion and internal reflection
(D) Dispersion, scattering and total internal reflection
Ans. Option (C) is correct.
Q 3 – The twinkling of stars is due to atmospheric.
(A) dispersion of light by water droplets
(B) refraction of light by different layers of varying refractive indices
(C) scattering of light by dust particles
(D) internal reflection of light by clouds
Ans. Option (B) is correct.
Q 4 – At noon the sun appears white as
(A) light is least scattered.
(B) all the colours of the white light are scattered away.
(C) blue colour is scattered the most.
(D) red colour is scattered the most.
Ans. Option (A) is correct.
Q 5 – The dear sky appears blue because
(A) blue light gets absorbed in the atmosphere
(B) ultraviolet radiations are absorbed in the atmosphere
(C) violet and blue lights get scattered more than light of all other colours by the atmosphere
(D) light of all other colours is scattered more than the violet and blue colour light by the atmosphere
Ans. Option (C) is correct.
Q 6 – Which of the following statements is correct regarding the propagation of light of different colours of white light in air?
(A) Red light moves fastest
(B) Blue light moves faster than green light
(C) All the colours of the white light move with the same speed
(D) Yellow light moves with the mean speed as that of the red and the violet light.
Ans. Option (C) is correct.
Q 7 – Which of the following phenomena contributes significantly to the reddish appearance of the sun at sunrise or sunset?(A) Dispersion of light
(B) Scattering of light
(C) Total internal reflection of light
(D) Reflection of light from the earth
Ans. Option (B) is correct.
Q 8 – In an experiment to trace the path of a ray of light through a triangular glass prism, a student would observe that the emergent ray.
(A) is parallel to the incident ray.
(B) is along the same direction of incident ray.
(C) gets deviated and bends towards the thinner part of the prism.
(D) gets deviated and bends towards the thicker part (base) of the prism.
Ans. Option (D) is correct.
Q 9 – Study the following figure in which a student has marked the angle of incidence (Li), angle of refraction (Zr), angle of emergence (Le), angle of prism (LA) and the angle of deviation (LD). The correctly marked angles are:
(A) LA and Li
(B) LA, Li and Zr
(C) LA, Li, Le and LD
(D) LA, Li, Zr and LD
Ans. Option (A) is correct.
(i) Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
(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 true
Q 10 – Assertion (A): A white light on passing through prism splits into its component colours as such that the red light emerges nearest to the base of the prism.
Reason (R): Wavelength of red light is more than other component colours and hence, red light deviates least.
Ans. Option (D) is correct
Q 11 – Assertion (A): Sunlight reaches us without dispersion in the form of white light and not as its components.
Reason (R): Dispersion takes place due to variation of refractive index for different wavelength but in vacuum the speed of light is independent of wavelength and hence vacuum is a non-dispersive medium.
Ans. Option (A) is correct
Q 12 – Assertion (A): In case of rainbow, light at the inner surface of the water drop gets internally reflected.
Reason (R): The angle between the refracted ray and normal to the drop surface is greater than the critical angle.
Ans. Option (A) is correct
Q 13 – Assertion (A): Scattering of light is the reflection of light from an object in all directions.
Reason (R): The colour of scattered light depends on the size of scattering particles and wavelength of light.
Ans. Option (B) is correct.
(ii) Attempt any 4 sub-parts from each question. Each sub-part carries 1 mark.
I.A narrow beam of white light is passing through a glass prism as shown in the diagram. Study the diagram and answer any four questions from Q.I. to Q.5.
Q 14 – The phenomenon observed in above set-up is
(A) scattering of light
(B) dispersion of light
(C) reflection of light
(D) refraction of light
Ans. Option (B) is correct.
Q 15 – In nature, this phenomenon is observed in
(A) Formation of rainbow
(B) Twinkling of stars
(C) Blue colour of sky
(D) Advance sunrise
Ans. Option (A) is correct.
Q 16 – Which of the following statement is correct about constituents of white light based on above observations?
(A) White light consists of seven colours.
(B) Violet colour suffers minimum deviation.
(C) Red light suffers maximum deviation.
(D) All the colours of the white light move with different speed in vacuum.
Ans. Option. (A) is correct.
Q 17 – The cause of dispersion of light is
(A) All the colors of light travel with the speed more than the speed of light.
(B) All the colors have different angles of deviation.
(C) All the colors do not travel with the same speed of light.
(D) All the colors have the same wavelength .
Ans. Option (C) is correct.
Q 18 –Read the following statements carefully
(A) The prism behaves same as that of rectangular glass slab.
(B) All the colours have different angles of deviation in case of dispersion through prism.
(C) All the colours travel with the same speed of light in glass.
(D) Dispersion of light is observed in case of rectangular glass slab.
Which of the above statements is true?
(A) Only (ii)
(B) (i) and (ii) only
(C) (i), (ii) and (iv) only
(D) All of the above
Ans. Option (A) is correct.