Question

The radius of curvature of concave mirror is 24 cm and the image is magnified by 1.5 times. The object distance is

• A. 20 cm
• B. 8 cm
• C. 16 cm
• D. 24 cm

Answer 1

The correct option is A 20 cm

Given that, $R=-24$cm
$f=-12cm$ and $m=1.5$
By the lens formula,
$\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$
$\frac{1}{1.5u}+\frac{1}{u}=-\frac{1}{12}$
$\frac{2.5}{1.5u}=-\frac{1}{12}$
or, $u=-20cm$