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Question
Three mirrors are created from a single sphere. Which of the following - pole, centre of curvature, radius of curvature, principal axis - will be common to them and which will not be common?

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Solution
Let us name the mirrors M1, M2 and M3 as shown below.

From the figure, we see that
- pole (P) is not common.
- centre of curvature (C) is common.
- principal axis (PA) is not common.
- radius of curvature (R) is common. The radius of curvature is the radius of the sphere. In the given figure, the length CP is the same for all mirrors.
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