Question

AssertionThe focal length of the objective of the telescope is larger than that of eyepiece.
Reason The resolving power of telescope increases when the aperture of objective is small.

• A. Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
• B. Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
• C. Assertion is correct but Reason is incorrect.
• D. Assertion is incorrect but Reason is correct.

Answer 1

Answer: (C)

The magnifying power of telescope is $m=\frac{f_{o}}{f_{e}}$.
So, for high magnification, the focal length of objective lens should be larger than eyepiece.
Resolving power of a telescope $=\frac{d}{1.22 \lambda}$.
For high resolving power, diameter $(d)$ of objective should be higher.