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GCSE questions on refraction and TIR

Q10.

(a) Here is a diagram of an optical fibre.

(i) What is the name given to the dotted line on the diagram?

The normal

[1 mark]

(ii) Where the ray of light touches the edge of the optical fibre it is reflected.

Draw the reflected ray onto the diagram.

The marks were awarded as follows:

reflected ray drawn to the right of the normal

correct ray of light drawn using a ruler with i = r

[2 marks]

(b) Optical fibres need to be able to bend around corners without breaking.

Suggest the property that optical fibres must have to allow them to bend around corners.

They need to be flexible

Examiners were told to ignore answers of 'bendy, ductile, malleable or elastic'

[1 mark]

(Total 4 marks)