Question

A point object $O$ is placed at a distance of $0.3m$ from a convex lens (focal length $0.2m)$ cut into two halves each of which is displaced by $0.0005m$ as shown in the figure.
Find the spacing between the images so formed.

• A. $0.1cm$
• B. $0.5cm$
• C. $0.3cm$
• D. $1cm$

Answer 1

Answer: (C)

$0.3cm$

Magnification for the upper half of the lens=$\frac{v}{u}=\frac{60}{-30}=-2$

Hence the distance of image and the upper dotted line is $2\times 0.05cm=0.1cm$

Similarly distance between image after refraction from lower half and lower dotted line=$0.1cm$

Total distance between images =$0.1cm+(2\times 0.05)cm+0.1cm=0.3cm$