Answers

2015-01-19T19:45:20+05:30
It is a point on the principal axis , where abeam of light parallel to the principal axis, after reflection , either actually meet or appears to meet . it is denoted by F
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2015-01-19T19:49:59+05:30
The point on the principle axis  of a concave mirror on which the beam of light ,parallel to principle axis meet after getting reflected is known as principle focus .
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