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प्रश्न
Explain the following term related to spherical lenses:- principal focus
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उत्तर
Principal Focus:-
The convex lens converge the rays incident on it after refraction, to a point on the principal axis. This point is known as principal focus of the convex lens. The rays incident on concave lens appear to diverge from a point on the principal axis. This point is known as the principal focus of concave lens.
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