Question

The linear magnification for a mirror is the ratio of the size of the image to the size of the object, and is denoted by ${}^{\prime }{m}^{\prime }$. Then $m$ is equal to $\left(\frac{-f}{u-f}\right)$ (symbols have their usual meanings)

• A. True
• B. False

Answer 1

The correct option is A True

$\text{From the mirror formulae}$

$\frac{1}{f}=\frac{1}{v}+\frac{1}{u}$.........(1)

multiplyng by u in eq.(1)

$\frac{u}{f}=\frac{u}{v}+\frac{u}{u}$

$\frac{u}{f}-1=\frac{u}{v}$

$\frac{u-f}{f}=\frac{u}{v}$

$\frac{f}{u-f}=\frac{v}{u}$

As $m=\frac{-v}{u}$

hence, $m=\frac{-f}{u-f}$