Question

In Young's double slit interference experiment the slit separation is made $3$ fold. The fringe width becomes

• A. $1/3$ times
• B. $1/9$ times
• C. $3$ times
• D. $9$ times

Answer 1

The correct option is A $1/3$ times

The fringe width is given as:

$\beta =\frac{D\lambda }{d}$

$\beta \propto \frac{1}{d}$

$\Rightarrow$ If $d$ becomes thric, then $\beta$ become becomes $\frac{1}{3}$