This question is about the behavior of visible light.
State how the speed of light changes when it travels from air into glass.
The diagram shows a ray of light travelling through air towards a flat glass block.

Complete the ray diagram to show the path of the ray after it enters the glass. Include a normal line in your diagram.
The diagram shows three parallel incident rays hitting the rough surface of a sheet of paper. Light is scattered from this surface.

Complete the diagram to show the scattered rays.
A student is wearing a T-shirt that appears blue under white light.
Explain why the T-shirt appears black when illuminated only by red light.