Question

The focal length of a concave mirror is 5cm. Its radius of curvature is a) 5 cm b) 10 cm c) 2.5 cm

Answer 1

when a ray of light parallel to principle axis strikes the surface of a concave mirror , converge at a fixed point is known as focus. And distance between foucs to pole of the mirror is known as focal length. Radius of curvature is two time of focal length. it is radius of spherical mirror(concave mirror).

so, radius of curvature = 2 × focal length
Given, focal length = 5 cm
∴ radius of curvature =2 × 5 = 10cm

Hence, (b) is correct

Answer 2

Explanation:

Focal length = 5cm

Radius of curvature = 2f

= 2×5 cm

= 10 cm

Option (,b) is correct...