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Question
The diagram below shows the parallel rays incident on a convex mirror. C is the centre of the curvature of the mirror. By drawing the paths of the reflected rays, label the focus F and hence find the focal length of the mirror.
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Solution
We know when the incident ray is parallel to the principal axis then they appear to diverge from a point F.
Geometrically we can find this value and this comes to 2 cm. Centre of curvature = 4 cm.
Focal length = centre of curvature/2.
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