The dispersive powers of the material of the two lenses are in the ratio of 4 3 . If the focal length of this achromatic combination is 60 cm , find the focal length of the lenses.

For an achromatic combination of lenses, f 1 f 2 = - ω 1 ω 2 . . . i here: ω 1 ω 2 = 4 3 . . . ii From the equation i and ii So, f 1 f 2 = - 4 3 or f 1 f 2 = - 4 3 f 2 . Now the combined focal length of the lens is given by 1 F = 1 f 1 + 1 f 2 1 60 = - 3 4 f 2 + 1 f 2 ∵ F = 60 cm 1 60 = - 3 + 4 4 f 2 4 f 2 = 60 ∴ f 2 = 15 cm and f 1 = - 4 3 f 2 f 1 = - 4 3 × 15 f 1 = - 20 cm . Hence, the focal length of component lenses is + 15 cm and - 20 cm .

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Beta Question Bank for Medical: Physics>Chapter 30 - Ray Optics>BEGINNER'S BOX - 7

Embibe Experts Solutions for Chapter: Ray Optics, Exercise 7: BEGINNER'S BOX - 7

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Embibe Experts Physics Solutions for Exercise - Embibe Experts Solutions for Chapter: Ray Optics, Exercise 7: BEGINNER'S BOX - 7

Attempt the practice questions on Chapter 30: Ray Optics, Exercise 7: BEGINNER'S BOX - 7 with hints and solutions to strengthen your understanding. Beta Question Bank for Medical: Physics solutions are prepared by Experienced Embibe Experts.

Questions from Embibe Experts Solutions for Chapter: Ray Optics, Exercise 7: BEGINNER'S BOX - 7 with Hints & Solutions

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Beta Question Bank for Medical: Physics>Chapter 30 - Ray Optics>BEGINNER'S BOX - 7>Q 1

In the displacement method, the distance between the object and the screen is $70 cm$ and the focal length of the lens is $16 cm$ , find the separation between the magnified and diminished image position of the lens.

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Beta Question Bank for Medical: Physics>Chapter 30 - Ray Optics>BEGINNER'S BOX - 7>Q 2

An achromatic doublet of focal length 90 cm si to be made of two lens. The material of one of the lenses has 1.5 times the dispersive power of the other. The doublet is converting type. Find the focal length of each lens.

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Beta Question Bank for Medical: Physics>Chapter 30 - Ray Optics>BEGINNER'S BOX - 7>Q 3

The dispersive power of material of a lens of focal length $20 cm$ is $0.08$ . Find the longitudinal chromatic aberration of the lens?

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Beta Question Bank for Medical: Physics>Chapter 30 - Ray Optics>BEGINNER'S BOX - 7>Q 4

The dispersive powers of the material of the two lenses are in the ratio of $\frac{4}{3}$ . If the focal length of this achromatic combination is $60 cm$ , find the focal length of the lenses.

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Beta Question Bank for Medical: Physics>Chapter 30 - Ray Optics>BEGINNER'S BOX - 7>Q 5

What is the axial chromatic aberration in case of a lens which focusses violet ray 20.1 cm and red ray 20.3 cm away from it.