Question

Focal length of a concave mirror, true or false:

1. It is always on the side of the mirror opposite of where the image forms

2. It is always negative

3. It is always positive

4. It is always equal to 1/2 the radius of the curvature of the mirror.

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So far I believe 3 and 4 are true and the rest are false.

Answer 1

Focal length of the the concave mirror is always negative and it is equal to the the half of the radius of curvature.

F is at opposite to the direction of light hence ,it is negative.

2and 4 are true.