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GCSE questions on refraction and TIR

Q4. The diagram shows how a ray of light from a laser travels along an optical fibre.

(a)     Explain why the ray of light stays within the optical fibre.

(2 marks)

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

Calculate the critical angle 'c' of this material given that sin c = 1/n

(2 marks)

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

The diagram 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)

(Total 7 marks)