Question

A convex of focal length 10 cm is placed at a distance of 12 cm from a wall how far from the lens should be an object be placed so as to form its real image on the wall.​

Answer 1

We have,

f=10 cm

v=12 cm

u=?

As 1/f = 1/v - 1/u

⇒u= -60 cm.

THANK YOU

Answer 2

Solution:- A convex of focal length 10 cm is placed at a distance of 12 cm from a wall.

Given,

Focal length = 10 cm

Image distance = 12 cm

Object distance = ?

According to the lens formula,

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

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

Substituting the values and solving, we get

$= > \frac{1}{u}= \frac{1}{12} - \frac{1}{10}$

$= \frac{5}{60} - \frac{6}{60}$

$= - \frac{ 1}{60}$

$u = - 60 \: cm$

Thus, the object should be kept at a distance of 60 cm in front of the convex lens. The negative sign indicates that the object is kept on the left side of the lens.