Question

The flat face of a plano-convex lens of focal length $10$cm is silvered. A point source placed $30$cm in front of the curved surface will produce a.

• A. Real image $5$cm away from the lens
• B. Real image $6$cm away from the lens
• C. Virtual image $15$cm away from the lens
• D. Virtual image $6$cm away from the lens

Answer 1

The correct option is C Virtual image $15$cm away from the lens

Focal length of plano-convex lens =10 cm

object distance $u=-30cm$

Using the lens equation

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

$\frac{1}{10}=\frac{1}{v}-\frac{1}{-30}$

$v=15cm$ and image is virtual.