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3.7 plan, choose equipment or resources and perform a first-hand investigation to model the process of accommodation by passing rays of light through convex lenses of different focal lengths
plan, choose equipment or resources and perform a first-hand investigation to model the process of accommodation by passing rays of light through convex lenses of different focal lengths
Background
A biconvex lens is shaped as shown in the diagram below. Convex lenses magnify images by causing rays of light to converge.
The lens in the human eye is a convex lens. When parallel rays of light are passed through a convex lens, they will converge at a point, known as the focal point.
The focal length of a lens is the distance of the focal point from the centre of the lens.
Convex lens
- This activity requires you to select glass or perspex lenses of different focal lengths and compare how they refract light. One possible method is to use a ray box and observe how the lenses refract light. Make sure that you compare how lenses of different focal lengths can focus objects at different distances away from the lens. As the curvature of the lens increases the focal length deceases. Remember that the same lens in the eye can vary its focal length by accommodation.