1.1. Extended tier only

An endoscope is a piece of medical equipment used to see inside a person's body. Endoscopes use optical fibres within a long tube which reflects light from inside the patient to an eye piece lens or camera. 

Fig. 1.1

Fig. 1.1 shows a section of optical fibre. Light travels from X to Y.

On Fig. 1.1, complete the path of the light ray until it leaves the section of optical fibre.

1.2. State the type of reflection that occurs within an optical fibre.

1.3. Extended tier only

Calculate the critical angle.

Glass has a refractive index of 1.52.

critical angle = ...................................

1.4. Extended tier only

When the light ray exits the optical fibre it passes into air. 

Calculate the speed of light in glass. 

speed of light in glass = ....................................