Double Slit Question?

A lamp emits light with wavelength of #580 nm.# This light passes through two small slits which causes interference and creates an interference pattern on the the screen #1.5 m# beyond the slits. If the spacing between the fringes of the interference pattern is #4.2mm#, how far apart are the slits?

1 Answer
anantha n.
Feb 25, 2018

Fringe width(spacing between fringes) #beta = lambda *D/d#
where , #lambda# is wavelength of light , D is distance between slit and screen and d is distance between the slits

So , #d = lambda*D/beta #
= # (580 * 10^-9 * 1.5 )/(4.2 * 10^-3 )m#
=#207.14 * 10^-6 m # = #0.207 mm#

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