AP EAMCET · PHYSICS · Ray Optics
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.
- A Both A and R are true and R is a correct explanation for A
- B Both A and R are true but R is not a correct explanation for A
- C A is true, R is false
- D Both A and R are false
Answer & Solution
Correct Answer
(D) Both A and R are false
Step-by-step Solution
Detailed explanation
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.
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