Question

The resolving power of a telescope depends on

• A. length of telescope.
• B. focal length of an objective.
• C. diameter of the objective.
• D. focal length of an eye piece.

Hint:

A larger objective lens diameter gives better resolving power in optical instruments.

Answer 1

The Correct Option is C

Step 1: Define resolving power.
Resolving power of a telescope is its ability to distinguish between two closely spaced distant objects.
Step 2: Formula for resolving power of telescope.
The angular resolving power is given by: \[ \theta_{\min} = \dfrac{1.22\lambda}{D} \] where $D$ is the diameter of the objective lens.
Step 3: Analyze dependence.
Smaller value of $\theta_{\min}$ means better resolving power, which is achieved by increasing the diameter of the objective.
Step 4: Final conclusion.
Thus, resolving power depends on the diameter of the objective.