Question

The ratio of resolving power of telescope, when lights of wavelength $4000\stackrel{o}{A}$ and $5000\stackrel{o}{A}$ are used, is _________.

• A. $6:5$
• B. $5:4$
• C. $4:5$
• D. $9:1$

Answer 1

Answer: (B)

$5:4$

Resolving power(R.P.) $\propto {\lambda }^{-1}$

Therefore $\frac{R.P{.}_1}{R.P{.}_2}=\frac{{\lambda }_2}{{\lambda }_1}$

Given:

${\lambda }_1=4000\stackrel{o}{A}$

${\lambda }_2=5000\stackrel{o}{A}$

Hence $\frac{R.P{.}_1}{R.P{.}_2}=\frac{5000\stackrel{o}{A}}{4000\stackrel{o}{A}}$

$\frac{R.P{.}_1}{R.P{.}_2}=\frac{5}{4}$

Therefore the correct option is (B).