Question

When an object is placed at a distance of 60 cm² from a convex theorical mirror , the magnification produced is 1/2. Where should the object be placed to a magnification of 1/3 ?

Answer 1

In the first part

In case of convex mirror, u= -60cm

m= 1/2 implies v= 30cm(Since image must be virtual)

On substituting in equation, 1/u + 1/v = 1/f

or f = uv/ u+v we get f=60cm

In IInd case, m= 1/3=0.33

m=(-v/u)

v=(-u/3)

f=60cm

Substituting  in f=uv/u+v

we get u= -2f =(-2) x 60 cm= -120 cm