Page 1 - Worksheet 3

WORK SHEET -3, PHYSICS

CLASS 12, CHAPTER 9 (RAY OPTICS AND OPTICAL INSTRUMENTS)

Prism, Dispersion and Scattering

1 Write the relationship between angle of incidence ‘i’, angle of prism ‘A’ and angle of
minimum deviation for a triangular prism. (Delhi 2013)

2 How does the angle of minimum deviation of a glass prism vary, if the incident violet
light is replaced by red light? Give reason. (Delhi 2017).
3 Define refractive index of a transparent medium. A ray of light passes through a
triangular prism. Plot a graph showing the variation of the angle of deviation with the
angle of incidence. (All India 2009)

4 In the formation of a rainbow, the light from the sun on water droplets undergoes
(a) dispersion only.
(b) only TIR.
(c) dispersion and TIR.
(d) scattering.
5 Two beams of red and violet color are made to pass separately through a prism
(angle of the prism is 60°). In the position of minimum deviation, the angle of
refraction will be
(a) 30° for both the colors
(b) greater for the violet color
(c) greater for the red color
(d) equal but not 30° for both the colors
6 Which of the following colours of white light deviated most when passes through a
prism?
(a) Red light
(b) Violet light
(c) Yellow light
(d) Both (a) and (b)
7 An object is immersed in a fluid. In order that the object becomes invisible, it should
(a) behave as a perfect reflector.
(b) absorb all light falling on it.
(c) have refractive index one.
(d) have refractive index exactly matching with that of the surrounding fluid.
8 A ray of light incident at an angle θ on a refracting face of a prism emerges from the
other face normally. If the angle of the prism is 5° and the prism is made of a material
of refractive index 1.5, the angle of incidence is [NCERT Exemplar]
(a) 7.5°
(b) 5°
(c) 15°
(d) 2.5°