Question

Two objects $A$ and $B$ are placed at $15cm$ and $25cm$ from the pole in front of a concave mirros having radius of curvature $40cm$. The distance between images formed by the mirror is

• A. $40cm$
• B. $160cm$
• C. $60cm$
• D. $100cm$

Answer 1

Answer: (B)

by mirror formula
$\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$
$\frac{1}{v_1}+\frac{1}{-15}=\frac{1}{(-20)}$
$\frac{1}{v_1}=-\frac{1}{20}+\frac{1}{15}$
$=\frac{-3+4}{60}$
$v_1=60cm$
$\frac{1}{v_2}+\frac{1}{(-25)}=\frac{1}{(-20)}$
$\frac{1}{v_2}=\frac{-1}{20}+\frac{1}{25}$
$=\frac{-5+4}{100}=\frac{-1}{100}$
$v_2=-100cm$
$d=60+100=160cm$