Sodium light $\left(\lambda=6 \times 10^{-7} \mathrm{~m}\right)$ is used to produce interference pattern.…

Sodium light $\left(\lambda=6 \times 10^{-7} \mathrm{~m}\right)$ is used to produce interference pattern. The observed fringe width is 0.12 mm . The angle between the two wave trains is
  1. $5 \times 10^{-1} \mathrm{rad}$
  2. $5 \times 10^{-3} \mathrm{rad}$
  3. $1 \times 10^{-2} \mathrm{rad}$
  4. $1 \times 10^{-3} \mathrm{rad}$

Solution

$\mathrm{W}=\frac{\lambda \mathrm{D}}{\mathrm{~d}}$
Angle between the two wave trains is $\begin{aligned} \frac{d}{D} & =\frac{\lambda}{W} \\ & =\frac{6 \times 10^{-7}}{0.12 \times 10^{-3}} \\ & =5 \times 10^{-3} \mathrm{rad} \end{aligned}$ ~

Asked in: MHT CET 2024 (15 May Shift 2)

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