Question
Sun February 24, 2008 By:

How to know that the given focal length/dictance is positive or negative

Expert Reply
Mon February 25, 2008

How to know that the given focal length/dictance is positive or negative.

It will give in the question that the mirror is concave/convex or lens is convex/concave.

The focal length of Concave mirror/Concave lens is negative while the focal length of convex mirror/convex lens is positive as per the New Sign Cartesian convention.

Rgds

Physics Expert

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