Question

A 2 cm high object is placed at a distance of 20 cm from a concave mirror are real image is formed at 40 cm of the mirror calculate focal length and size of image

Answer 1

here is ur answer dude

Answer 2

"Given:

The given question states the distance of the object from the mirror denoted as u is 20 cm and is to be taken as negative due to sign convention.

The distance of the image from the mirror denoted as v is 40 cm and is also to be taken negative.

The height of the object is 2cm.

Solution:

We can apply the mirror formula,

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

$\frac{1}{-40}+\frac{1}{-20}=\frac{1}{f}$

$\frac{-1-2}{40}=\frac{1}{f}$

$f=-\frac{40}{3}$

f = - 13.33 cm

Magnification is calculated by the formula given below,

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

$m=\frac{\text {Height of image}}{\text {Height of object}}$

$-\frac{v}{u}=\frac{\text {Height of image}}{\text {Height of object}}$

$-\left(\frac{-40}{-20}\right)=\frac{\text {Height of image}}{2}$

Height of image = -4 cm"