Question

Focal length of a concave mirror depends on its

• A. size.
• B. aperture.
• C. radius of curvature.
• D. material used.

Answer 1

The correct option is C

radius of curvature.

Explanation for the correct option(s)- Option (c)

• The focal length of a concave mirror depends on the radius of curvature as the radius of curvature is twice the focal length. Mathematically, $R=2f$, where $R$ is the radius of curvature and $f$ is the focal length.
• Thus, $f=\frac{R}{2}$.

Explanation for the incorrect option(s)-

Option (a)

Focal length is independent of the size of the mirror.

Option (b)

Focal length is independent of the aperture of the mirror.

Option (d)

Focal length is independent of the material of the mirror.

Final answer - Hence, option (c) is the correct answer.