Question

а) a concave mirror has a radius of 40cm. An object is placed at a distance of 20cm
from the pole on its principle axis. Find
the position of the image formed by the
mirror​

Answer 1

$\huge\text{\underline{Answer}}$

$\sf{\underline{Given }}$

radius of mirror = - 40 cm

Object distance (U)= - 20 cm

- sign is shows that the radius and object lies on L. H. S. from the pole.

$\sf{\underline{To find}}$

Image distance = ?

$\huge\sf{solution:}$

We will use here Mirror formula.

$\boxed{\sf{ \frac{1}{f} = \frac{1}{u} + \frac{1}{v} }}$

where, f is focal length and u is object distance and v is image distance.

first we have to find focal length of mirror.

$\boxed{\sf{f =\frac{R}{2} }}$

$\implies$ $\bold{f = \frac{ - 40}{2} }$

$\implies$ $\bold{f = -20 cm}$

Now by using mirror formula.

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

$\implies$ $\bold{ \frac{1}{v} = \frac{ - 1}{20} - \frac{1}{( - 20)} }$

$\implies$ $\bold{\frac{1}{v} = \frac{ - 1}{20} + \frac{1}{20} }$

$\implies$ $\bold{ \frac{1}{v} = \frac{ - 1 + 1}{20} }$

$\implies$ $\bold{v = \infty }$

hence,object will formed on $\infty$