The diagram below shows how a ray of light from a laser travels along an optical fibre.

a) Why does the ray of light stay within the optical fibre?

(1 mark)

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(b) The material used to make the optical fibre has a refractive index of 1.50.

Calculate the critical angle of this material.

Use the correct equation from the Physics Equations Sheet.

Critical angle = .............................  degrees

(2 marks)

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(c) Different wavelengths of light can be used to transmit information along optical fibres.

The graph below shows how the percentage of incident light transmitted through a fibre varies with the wavelength of light and the length of the fibre.

Compare the percentages of incident light transmitted through the two different fibres over the range of wavelengths shown.

(3 marks)

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From Q7 P3 AQA June 2014 (Higher)