(a) Lenses can be used to help people see clearly.

Complete the ray diagram for part (a) to show how the light rays travel through and emerge from this model concave lens (glass prisms and glass block).
Explain how a concave lens can correct short-sighted vision. Use the model to help you.
A student looks at blue paper in different coloured light. She looks at the blue paper with blue light. The paper appears blue. What colour does the blue paper appear in red light? Explain your answer.