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RAY OPTICS AND OPTICAL INSTRUMENTS

Physics
Inter Second Year
English
Very Short Answer Questions
Q1. What do you understand by the terms ‘focus’ and‘principal focus’ in the context of lenses?

Answer
Ans.

Focus:It is the point at which rays converge or from which they appear to diverge.

Principal focus: It is the point, at which rays parallel to the principal axis converge (in case of a concave lens), or from which they appear to diverge (in case of a concave lens).