CBSE - X - Physics - Light - Reflection and Refraction
How to know that the given focal length/dictance is positive or negative
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.
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