Question

Define the focus (or focal point) and focal length of a convex mirror.

Answer 1

Step 1: Defining focus of the convex mirror

1. Convex mirror is defined as the diverging mirror in which the outer bulging part of the hollow sphere is coated.
2. Focus of a convex mirror is defined as the point in the principal axis where the reflected rays diverge after the parallel rays of light is incident on the surface of the mirror.
3. Focus of a convex mirror is formed behind the lens, which means the images are virtual.

Step 2: Defining focal length of a convex mirror

• The focal length (f) is defined as the distance between the pole and the focus.
• Radius of curvature (R) is defined as the radius of the hollow sphere of which the mirror is a part.
• The relationship between the focal length and the radius of curvature of a convex mirror is $f=\frac{R}{2}$.