Question

An object is kept at a focus of a concave lens of focal length 30cm then find the position of image

Answer 1

Object distance (u) = - 30 cm

Focal length (v) = - 30 cm

Let the image distance from the lens be v.

Formula to find image distance:

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

Plugging the values:

$\frac{1}{v} + \frac{1}{30} =-\frac{1}{30}$

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

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

v = - 15 cm

The image will be formed on the same side where the object is kept at a distance of 15 cm.