Advertisement

Advertisement

MCQ

**Choose the correct answer from given options**A biconvex lens of focal length f is cut into two identical plano-convex lenses. The focal length of each part will be

#### Options

f

f/2

2f

4f

Advertisement

#### Solution

Let the focal of the equiconvex lens be f and that of the plano-convex lens be f'.

Let the radius of curvature for the equiconvex lens be R.

Applying Lens maker's formula

`1/f = (mu - 1)(1/R + 1/R) = (2(mu - 1))/R`

For the plano-convex lens, the focal length can be calculated as:

`1/f' = (mu - 1)(1/R) = (mu - 1)/R`

Thus, f' = 2f

Thus, the focal length of the plano-convex lens is twice that of the equiconvex lens.

Hence, the correct answer is option** 2f.**

Concept: Lenses

Is there an error in this question or solution?