Question

The ratio of the speed of an object to the speed of its real image of magnification $ m $ of a convex mirror is

• A. $ -\frac{1}{m^2} $
• B. $ m^2$
• C. $ -m $
• D. $ \frac{1}{m} $

Answer 1

Answer: (A)

$\frac{1}{u}+\frac{1}{v}=\frac{1}{f}$
$-\frac{1}{u^{2}} \frac{d u}{d t}-\frac{1}{v^{2}} \frac{d v}{d t}=0$
$=-\frac{1}{u^{2}} u_{0}-\frac{1}{v^{2}} v_{0}=0$
$\frac{u_{0}}{v_{0}}=-\frac{u^{2}}{v^{2}}=-\frac{1}{m^{2}}$