NEET 2023, Physics Q37: Thin Lens and Mirrors

NEET2023Physics

Two thin lenses are of same focal lengths ( $f$ ), but one is convex and the other one is concave. When they are placed in contact with each other, the equivalent focal length of the combination will be:

A
$f /4$
B
$f /2$
C
Infinite
D
Zero

Solution

The convex lens has focal length $+ f$ and the concave $- f$ .

$\frac{1}{f _{e q}} = \frac{1}{f} + \frac{1}{- f} = 0 \Rightarrow f_{e q} = \infty$ .

The combination has zero power and acts like a plane slab.

Concept behind this question

Thin Lens and MirrorsNotes, formulas and examples →

Practice more Physics

Concept-wise practice with instant solutions on Fundamenthol.

Start practicing →

NEET 2023, Physics Q37: Thin Lens and Mirrors

Concept behind this question

More previous year questions on Thin Lens and Mirrors

Practice more Physics