Question

A beam of light passing through a diverging lens of focal length 0.3m appear to be focused at a distance of 0.2m behind the lens. Find the position of the object

Answer 1

Given:

• Diverging lens of focal length$= 0.3m$

• $v = +0.2 m$

To Find:

• The position of the object

Solution:

Since ray passes through a diverging lens,

 So,            $f= -0.3m$

The object is also virtual

So,

         $v= +0.2m$

The lens formula  is given by

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

Putting the values

⇒     $\frac{1}{-0.3} = \frac{1}{0.2} - \frac{1}{u}$

           $\frac{1}{u} = \frac{1}{0.3} + \frac{1}{0.2}$

           $\frac{1}{u} = \frac{50}{6}$

           $u = 0.12m = 12cm$

Thus, if there hadn’t been the lens the rays would have met at a distance 12 cm behind the lens.

​  

 

 

Answer 2

above is the correct answer