Question

An object of 5 cm height is placed at a distance of 12 cm in front of a concave mirror.
it forms a real image 4 times larger than the object. Calculate the distance of the
image from the mirror.​

Answer 1

Given :

Height of the object = 5 cm

Object distance = 12 cm

Magnification = 4 cm

To find :

The distance of the image.

Solution :

we know that,

» The linear magnification produced by a mirror is equal to the ratio of the image distance to the object distance with a minus sign that is,

$\sf Magnification = - \dfrac{Image \: distance}{Object \: distance}$

(or)

$\sf m = -\dfrac{v}{u}$

where,

• m is magnification
• v is image distance
• u is object distance

by substituting all the given values in the formula,

$\dashrightarrow\sf m = -\dfrac{v}{u}$

$\dashrightarrow \sf 4 = -\dfrac{v}{ - 12}$

$\dashrightarrow \sf 4 = \dfrac{v}{ 12}$

$\dashrightarrow \sf v = 4 \times 12$

$\dashrightarrow \sf v = 48 \: cm$

Thus, the position of the image is 48 cm.