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Using Young's double slit experiment, a monochromatic light of wavelength 5000 \mathrm{\AA} produces fringes of fringe width 0.5 \mathrm{~mm}. If another monochromatic light of wavelength 6000 \mathrm{\AA} is used and the separation between the slits is doubled, then the new fringe width will be :

Option: 1

0.5\mathrm{mm}


Option: 2

1.0\mathrm{mm}


Option: 3

0.6\mathrm{mm}


Option: 4

0.3\mathrm{mm}


Answers (1)

best_answer

Fringe width (\omega) \mathrm{=\frac{D\lambda }{d}}

Fringe width (\omega) \mathrm{\alpha \ \ \frac{\lambda }{d}}

\mathrm{\frac{\omega^{\prime}}{\omega}=\frac{\lambda^{'} / d'}{\lambda / d}=\frac{\lambda^{\prime}}{\lambda} \times \frac{d}{d^{\prime}}}\mathrm{=\frac{6000}{5000} \times \frac{d}{2 d}} =\mathrm{\frac{6}{10}=0.6}

\begin{aligned} \mathrm{\omega ^{\prime} =\omega \times 0.6} \\ \end{aligned}\begin{aligned} \mathrm{=0.5 \times 0.6=0.3 \mathrm{~mm}} \\ \end{aligned}

Hence, the correct answer is Option (4).

Posted by

Divya Prakash Singh

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