Question

You place an object 30.0 cm from a concave mirror of 15.0 cm focal length. The object is 1.8 cm tall. Find the image position and image height.

Answer 1

Answer:30 cm

Explanation:

Given

object distance $u=30\ cm$

focal length of concave mirror $f=15\ cm$

height of object $h_o=1.8\ cm$

Using mirror formula

$\Rightarrow \frac{1}{v}+\frac{1}{u}=\frac{1}{f}$

$\Rightarrow \frac{1}{v}=\frac{1}{15}-\frac{1}{30}$

$\Rightarrow \frac{1}{v}=\frac{2-1}{30}$

$\Rightarrow v=30\ cm$

and magnification is

$\Rightarrow m=\frac{-v}{u}=\frac{h_i}{h_o}$

$\Rightarrow \frac{-30}{30}=\frac{h_i}{1.8}$

$\Rightarrow h_i=-1.8\ cm$

So height of object is same as of object .

Position :image is formed at the spot where object is placed.