Question

the radius of curvature of a concave mirror is 15 cm .its focal length will be​

Answer 1

radius of curvature =2x focal length

given radius of curvature of concave mirror is =15cm

2f=15

f = 15/-2

f=-7.5

therefore focal length = 7.5 cm

Answer 2

Answer:

Focal length will be​ 7.5 cm

Explanation:

• Spherical mirror can be of two types. They are concave mirror and convex mirror.

• Concave mirror: The spherical mirror in which the bulging in surface behaves like a reflection surface is called concave mirror.
• Radius of curvature: Spherical mirror is part of a sphere. The length between the centre of spherical part(concave mirror) and pole of the mirror is radius of the mirror.

          This radius is called radius of curvature. This is represented by the symbol 'r'.

• Focus: The point at which light rays meet after reflection from the concave mirror for parallel incident rays is called focus.
• Focal length: The distance between focus and pole of the mirror is call focal length. The focal length is represented by 'f'.
• We know that f = r/2     (r= 15 cm)

                              f = 15/2 = 7.5 cm