Question

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

Answer 1

48centimetres as d=magnification×object distance

Answer 2

Answer: The distance of the image is 48 cm.

Solution:

The object placed in front of the concave mirror forms a real image which is a magnified image, so the distance of image is calculated by the known formula of optics.

As we know that the magnification m = 4 which will be taken as negative as per the sign convention used taking the real image of the ray diagram to be negative. Hence m = - 4

Given that the distance of object u = 12 which is also taken negative due to sign convention, hence u = -12 cm

As we know, magnification is given by $\bold{m=\frac{-v}{u}}$

$\begin{array}{l}{m=\frac{-v}{u}} \\ {-4=\frac{-v}{-12}}\end{array}$

$- v = -4 \times -12$

-v = -48

v = 48 cm