Solve Study Textbooks Guides

Use app

Login

>>Class 12
>>Physics
>>Ray Optics and Optical Instruments
>>Combination of Lenses
>> $Two plano convex lenses of same material$

Question

Two plano convex lenses of same material and of focal lengths 20 cm & 5 cm should be arranged such that the combination is free from chromatic aberration. Then effective focal length of the combination will be:

A

20 cm

B

4 cm

C

12.5 cm

D

8 cm

Medium

Open in App

Updated on : 2022-09-05

Solution

Verified by Toppr

Correct option is C)

The effective focal length of the lens is,

$\frac{1}{f} = \frac{1}{f _{1}} + \frac{1}{f _{2}} - \frac{f _{1} + f _{2}}{2 f _{1} f _{2}}$

Substituting the respective values, the effective focal length obtained is, $f = 12.5$

Solve any question of Ray Optics and Optical Instrument with:-

Patterns of problems

Was this answer helpful?

0

0

Similar questions

A combination of the two thin lenses of the same material with focal length, $f_{1}$ and $f_{2}$ are arranged on a common axis. In order to minimize the chromatic aberration, the distance between them should be :

Two plano-convex lenses of focal lengths $f$ and $2 f$ are coaxially separated so that the spherical aberration is minimized. The effective focal length of the combination is :

Two plano convex lenses of focal lengths $f_{1}$ and $f_{2}$ set for minimising spherical aberration are kept apart by 2 cm. If the equivalent focal length of combination is 10 cm, the values of $f_{1}$ and $f_{2}$ are :

Two lenses of focal lengths $+ 10$ cm and $- 15$ cm when put in contact behave like a convex lens. They will have zero longitudinal chromatic aberration if their dispersive powers are in the ratio

Two plano-convex lenses of same material and of focal lengths $f$ and $2 f$ are coaxially separated by a suitable distace to minimize chromatic aberration. The equivalent focal length of the combination is

More From Chapter

Ray Optics and Optical Instruments

View chapter >

Revise with Concepts

Combination of Lenses in Contact

ExampleDefinitionsFormulaes

Problems on Lenses

ExampleDefinitionsFormulaes

Learn with Videos

Power of a Lens

Effective Focal Length

Numericals on Combination of Lenses

Complex Numericals based on Thin Lenses

Shortcuts & Tips

Important Diagrams

Memorization tricks

Problem solving tips

Common Misconceptions

Practice more questions

Medium Questions