Question

The linear magnification of a convex mirror of focal length 15 cm is `1/3`. What is the distance of the object from the focus of the mirror ?

Answer 1

Here, `m=1/3,f=15cm,u=?`
From `m=v/-u=1/3` ` v = -u/3`
From `(1)/(v) + 1/u =(1)/(f)`
`-3/u +1/u =1/15`
u = -30cm.
This is the distance of the object from pole of the mirror i.e. `PO= -30 cm` . Distance of object from focus of mirror `OF =OP +PF=30+15 =45 cm`