A double-slit experiment is performed with blue-green light of wavelength 512 nm. The slits are 1.2 mm apart and the screen is 5.4 m from the slits. We have to find the distance between the bright fringes as seen on the screen.
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Solution: Click For PDF Version I n
the Young’s double-slit, the condition for interference maxima
at small angles is
where y is the distance on the screen of the interference maxima from the midpoint of the interference pattern, and D is the distance of the screen from the slits. Therefore, the distance between the successive bright fringes will be
We use the data of the problem;
We find
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As
angle
is small, we approximate
,
and
.