Question

A concave mirror pe produes three times.
enlanged image of an object plaut at 10cm in
front of it. Calculate the focal length of the
mirror​

Answer 1

m = 3 (virtual image)

u = - 10 cm

R = ?

We know that

m = - (v/u)

3 = -v/(-10)

V = 30 cm

And

1/v + 1/u = 1/f

1/30 + 1/(-10) = 1/f

-20/300 = 1/f

f = - 15 cm

Radius of curvature = R = 2f

= 2 × (-15) = - 30 cm