NEET Physics: Optical Instruments questions with solutions

Q1. Astigmatism for a human eye can be removed by using an additional:

1. concave lens
2. convex lens
3. cylindrical lens
4. prismatic lens

Answer: cylindrical lens

Astigmatism happens when the eye’s curvature is uneven, so light focuses differently in different meridians. A cylindrical lens provides power in one direction only, correcting that uneven focusing.

Q2. Assertion If objective and eye lenses of a microscope are interchanged then it can work as telescope. Reason The objective lens of telescope has small focal length.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Answer: Assertion is correct but Reason is incorrect

The assertion is correct because swapping the objective and eyepiece can make the setup behave like a telescope. The reason is incorrect: a telescope’s objective lens has a large focal length, not a small one.