In a biprism experiment , the distance of the `15` th bright band from the centre of the interference pattern is 6 mm . Calculate the distance of the
In a biprism experiment , the distance of the `15` th bright band from the centre of the interference pattern is 6 mm . Calculate the distance of the 25th bright band and 31st dark band .
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Given, 15th bright β = 6 mm
β = \(\frac{\lambda D}d\)
6 mm = \(\frac{15D\lambda}{d}\)
\(\frac{\lambda D}d=\frac6{15}\)
(i) 25th bright band
β = \(\frac{n \lambda D}d\)
β = \(\frac{25\lambda D}d\) (\(\because\) n = 25)
\(\because \frac{\lambda D}d=\frac6{15}\)
β = \(\frac{25\lambda D}d\)
β = 25 x \(\frac6{15}\)
β = 30/3
β = 10 mm
fringe width for dark band
β = (2n + 1)\(\frac{\lambda D}d\)
fringe = (2 x 31 + 1) \(\frac{\lambda D}d\)
β = 63\(\frac{\lambda D}d\)
β = 63 x \(\frac6{15}\)
β = 25.2 mm
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