Sec 3 Physics Assignment 2 – Refraction of Light
1)The figure below (not drawn to scale) shows white light incidence on face of a diamond. The white light is dispersed into its various rays. Only the red (R) and blue (B) rays are shown in Fig.
(a) Explain why white light disperses as it enters the diamond. [2]
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(b) Calculate the refractive index of diamond for blue light. [2]
(c)Calculate the speed of blue light in the diamond. [1]
(d)Without calculating, compare the speed of red light in diamond to the speed of
bluelight in diamond. [2]
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(e) Calculate the critical angle for diamond. [2]
(f)Describe and explain what happens to the blue ray once is hit the left side of the
diamond as shown infigure overleaf. [2]
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2) The figure shows a ray of light XYZ passing along a simple optical fibre to its end at Z.
(a)(i)Name the special effect shown when the ray XY does not leave the optical fibre at
Y. [1]
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(ii) Is the angle of 60 greater or smaller than the critical angle of the glass?
Give your reason for your answer. [2]
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(b) Explain why the ray YZ changes direction at Z. [2]
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(c) The refractive index of the glass is 1.6. The ray YZ makes an angle of 20 with the
normal tothe glass surface at Z. Calculate the angle P. [2]
3) A layer of oil (n = 1.45) floats on water (n = 1.33). A ray of light shines onto the oil
with an incidence angle of 40.0. Find the angle the ray makes in the water (with
respect to the normal). [5]
4) A plane mirror lies at the bottom of a long flat dish containing water, the mirror
making an angle with the horizontal as shown in the diagram below. The refractive
index of water is 1.33. When a light ray was incident on the surface of the water at P,
it traced out the path as shown in the diagram below.
(a) Calculate the critical angle for water. [2]
(b)Indicate the critical angle and label as c on the above diagram. [1]
(c) Calculate the angle of refraction at P. [2]
(d) Calculate the angle of reflection at the point where the light ray reflected off
the mirror surface. [2]
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