Question

In YDSE experiment with identical slit, the distance from central maxima where we get intensity half of maximum is [`D` , `d` and $\lambda$ have usual meaning]

• A. $\frac{\lambda d}{2d}$
• B. $\frac{3\lambda D}{4d}$
• C. $\frac{3\lambda D}{2d}$
• D. $\frac{2}{3}\frac{\lambda D}{d}$

Answer 1

The correct option is B $\frac{3\lambda D}{4d}$


$I=2I_0\text{for}\varphi =\frac{\pi }{2},\frac{3\pi }{2},\frac{5\pi }{2}$
$\Delta x=\frac{\lambda }{4},\frac{3\lambda }{4},\frac{5d}{4}.....\frac{dy}{D}=\Delta xy=\frac{\Delta xD}{d}=\frac{\lambda D}{4d},\frac{3\lambda D}{4d},\frac{5\lambda D}{4d}$