Question

For a light of wavelength $800\text{nm}$, the limit of resolution of a telescope is found to be equal to $\alpha$. The limit of resolution for light of wavelength $400\text{nm}$ will be

• A. $\alpha$
• B. $\frac{\alpha }{2}$
• C. $2\alpha$
• D. $3\alpha$

Answer 1

The correct option is B $\frac{\alpha }{2}$

Limit of resolution of a telescope is given by

$\alpha =\frac{1.22\lambda }{a}$, where $a$ is aperture size

Thus, as wavelength becomes half, the limit of resolution will also become half.

${\alpha }^{{}^{\prime }}=\frac{\alpha }{2}$