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IGCSE Refractive Index

The document describes light waves incident on the boundary between two different media - ice and air. 1) It provides the speed of light in air (3.0 x 108 m/s) and the refractive index of ice (1.3). 2) It asks the reader to draw the refracted wavefronts and direction of travel in the air, and label the angle of incidence and refraction on a diagram. 3) It asks the reader to calculate the speed of light in the ice using the information provided.

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Wei Peng Ten
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849 views4 pages

IGCSE Refractive Index

The document describes light waves incident on the boundary between two different media - ice and air. 1) It provides the speed of light in air (3.0 x 108 m/s) and the refractive index of ice (1.3). 2) It asks the reader to draw the refracted wavefronts and direction of travel in the air, and label the angle of incidence and refraction on a diagram. 3) It asks the reader to calculate the speed of light in the ice using the information provided.

Uploaded by

Wei Peng Ten
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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8 Fig. 8.1 shows parallel wavefronts of a light wave in ice. The wavefronts are incident on a boundary
with air.

direction
of wave

ice

air

Fig. 8.1

The speed of the light wave in air is 3.0 × 108 m / s. The refractive index of the ice is 1.3.

(a) On Fig. 8.1:

(i) draw the wavefronts of the wave that passes into the air [3]

(ii) draw arrows to show the direction of travel of the refracted wave [1]

(iii) label the angle of incidence i and the angle of refraction r. [1]

(b) Calculate the speed of the light wave in the ice.

speed = ......................................................... [2]

[Total: 7]

© UCLES 2019 0625/42/F/M/19


12

6 Green light of frequency 5.7 × 1014 Hz is travelling in air at a speed of 3.0 × 108 m / s. The light is
incident on the surface of a transparent solid.

Fig. 6.1 shows the wavefronts and the direction of travel of the light in the air.

wavefront

air
solid

Fig. 6.1

The light travels more slowly in the transparent solid.

(a) Explain, in terms of the wavefronts, why the light changes direction as it enters the solid. You
may draw on Fig. 6.1 as part of your answer.

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

............................................................................................................................................. [3]

(b) The refractive index of the transparent solid is 1.3.

(i) The light is incident on the surface of the solid at an angle of incidence of 67°.

Calculate the angle of refraction of the light in the solid.

angle of refraction = ......................................................... [2]

© UCLES 2019 0625/41/M/J/19


13

(ii) Determine the wavelength of the green light in the transparent solid.

wavelength = ......................................................... [4]

[Total: 9]

© UCLES 2019 0625/41/M/J/19 [Turn over

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