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10. Wave optics — Physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 SciencePhysics10. Wave optics1 Mark
MCQ
If prism angle $\alpha = 1^\circ ,\;\mu = 1.54,$distance between screen and prism $(b) = 0.7\,m,$ distance between prism and source $a = 0.3\,m,\;\lambda = 180\pi \;nm$ then in Fresnal biprism find the value of $\beta $ (fringe width)
  • ✓
    ${10^{ - 4}}m$
  • B
    ${10^{ - 3}}mm$
  • C
    ${10^{ - 4}} \times \pi m$
  • D
    $\pi \times {10^{ - 3}}m$
✓

Answer

Correct option: A.
${10^{ - 4}}m$
a
(a)By using $\beta = \frac{{(a + b)\lambda }}{{2a(\mu - 1)\alpha }} = \frac{{(0.3 + 0.7) \times 180\pi \times {{10}^{ - 9}}}}{{2 \times 0.3(1.54 - 1) \times \left( {1 \times \frac{\pi }{{180}}} \right)}}$= ${10^{ - 4}}m$

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