Question

Fringe width observed in the Young's double slit experiment is $\beta$. If the frequency of the source is doubled, the fringe width will

• A. remain $\beta$
• B. become $\frac{\beta }{2}$
• C. become $2\beta$
• D. remain $\frac{3\beta }{2}$

Answer 1

The correct option is B become $\frac{\beta }{2}$

Width of fringe = $\beta$
If frequency is doubled then, wavelength becomes halved, because velocity of light in air remains same
$\beta \propto \lambda \Rightarrow \frac{{\beta }^{\prime }}{\beta }=\frac{{\lambda }^{\prime }}{\lambda }=\frac{\frac{\lambda }{2}}{\lambda }=\frac{1}{2}{\beta }^{\prime }=\frac{\beta }{2}$