Question

A beam of light converges at a point P. Now convex lens of focal length 20 cm placed the path of the convergent beam 12 cm from the point at which the beam converges now

• A. 7.5 cm right side of the lens
• B. 7.5 cm left side of the lens
• C. 15.2 cm right side of lens
• D. 15.2 left side of lens

Answer 1

The correct option is A 7.5 cm right side of the lens

The correct option is A.

Given,

Object distance, $u=+12cm$ (virtual object)

The focal length of the convex lens, $f=20cm$

Image distance $=v$

Applying lens formula

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

Therefore, putting the values and solving the equation,

$\frac{1}{20}=\frac{1}{v}-\frac{1}{12}$

We get $v=\frac{60}{8}=7.5cm$

Thus, the image is formed $7.5cm$ away from the lens, toward its right.