Question

a concave mirror produces 3 times larger image with object distance 10 cm. find focal length ​

Answer 1

Answer:

As per the given conditions,

m = -3 {A concave mirror produces three times enlarged image of an object and the }

u = -10 cm

Formula

We know that,

m=−vu

Substituting the known values we get,

– 3 = (-v)/(-10)

v = – 30

The distance between the mirror and image =  – 30 cm

From mirror formula, we know

1v+1u=1f 1−30+1−10=1f

(-4)/30 = 1/f

or f = – 30/4

f = -7.5cm

The radius of curvature R = 2f

∴ R = 2 × (- 7.5)

R = – 15 cm