Assertion (A): The focal length of lens does not change when red light is replaced by blue light. Reason…

Assertion (A): The focal length of lens does not change when red light is replaced by blue light.

Reason (R): The focal length of lens does not depend in colour of light used.

  1. Both A and R are true and R is a correct explanation for A
  2. Both A and R are true but R is not a correct explanation for A
  3. A is true, R is false
  4. Both A and R are false

Solution

Focal length of the lens depends upon its refractive index as 1f∝μ-1.

Therefore, the focal length of a lens decreases when red light is replaced by blue light.

Asked in: AP EAMCET 2021 (20 Aug Shift 2)

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