Question

The angular resolution of a 10cm diameter telescope at a wavelength of $5000A^0$ is of the order of -

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

Answer 1

The correct option is B ${10}^{-6}rad$

Given parameters are,

Wavelength $\lambda =5000A^{\circ }$

= $5000\times {10}^{-10}$

Diameter of telescope, $D=10cm=0.1m$

Now, Angular resolution (d\theta) formula for telescope is,

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

Substituting the values, we get

$\Rightarrow d\theta =\frac{1.22\times 5000\times {10}^{-10}}{0.1}=6.1\times {10}^{-6}$

Clearly it is having significance order of ${10}^{-6}$.

Thus option B is correct.