Question

Resolving power of telescope increases when

• A. wavelength of light decreases.
• B. wavelength of light increases.
• C. focal length of eye-piece increases.
• D. focal length of eye-piece decreases.

Answer 1

Answer: (A)

Formula used
Resolving power of telescope
$\text{RP=}\frac{1}{\text{limit of resolution}}=\frac{a}{1.22\lambda }$
where $\text{ a}$ is the diameter of objective lens and $\lambda$ Is the wavelength of light.
Thus, clearly, $\text{RP ∝ a and RP ∝ }\frac{1}{\lambda }$
If the wavelength of the incident light is fixed, then we can increase the resolving power by increasing the diameter of the objective lens.
Resolving power of telescope increases when wavelength of light is decreased.