Question:medium
In a biprism experiment, fifth dark fringe is obtained at a point. A thin transparent film of refractive index '\(\mu\)' is placed in one of the interfering paths. Now \(7^{\text{th}}\) bright fringe is obtained at the same point. If '\(\lambda\)' is the wavelength of light used, the thickness of film is equal to
In a biprism experiment, fifth dark fringe is obtained at a point. A thin transparent film of refractive index '\(\mu\)' is placed in one of the interfering paths. Now \(7^{\text{th}}\) bright fringe is obtained at the same point. If '\(\lambda\)' is the wavelength of light used, the thickness of film is equal to
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Film shift:
$(\mu -1)t$ changes path difference
Updated On: May 8, 2026
- \(1.5(\mu - 1)\lambda\)
- \(\frac{1.5\lambda}{(\mu - 1)}\)
- \(2.5(\mu - 1)\lambda\)
- \(\frac{2.5\lambda}{(\mu - 1)}\)
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The Correct Option is D
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