Question

The radius of curvature of a spherical mirror is 30cm. What will be its focal length if (i) the inside surface is silvered? (ii) outside surface is silvered?

Answer 1

Dear Student,

◆ Answer -

(i) f = +15 cm

(ii) f = -15 cm

● Explanation -

Magnitude of focal length of mirror is always half of its radius of curvature.

Focal length of miiror will be -

|f| = R/2

|f| = 30/2

|f| = 15 cm

(i) When inside surface of mirror is silvered ?

• This will form a convex mirror. Focal length of convex mirror is positive, hence here focal length will be +15 cm.

(ii) When outside surface of mirror is silvered ?

• This will form a concave mirror. Focal length of concave mirror is negative, hence here focal length will be -15 cm.

Thanks dear...

Answer 2

Answer:15cm

Explanation:Radius of curvature=30cm

Focal length= R/2

a)the inside surface=30/2

=15 cm