Question

The angular resolution of a $10cm$ diameter telescope at a wavelength of $5000A$ is of the order of

• A. ${10}^{6}rad$
• B. ${10}^{-2}rad$
• C. ${10}^{-4}rad$
• D. ${10}^{-6}rad$

Answer 1

Answer: (D)

${10}^{-6}rad$

Given $\lambda =5000A^{\circ }=5\times {10}^{-7}m$

$d=10cm=0.1m$

Angular resolution of a telescope,

$\theta =\frac{1.22\lambda }{d}$

$\Rightarrow \theta =\frac{1.22\times 5\times {10}^{-7}}{0.1}$

$\Rightarrow \theta =6.1\times {10}^{-6}rad$

Hence the angular resolution is of the order ${10}^{-6}rad$.

The correct answer is option (D).