Q130 / 180 · NEET 2016 (Phase 1) · Physics

The intensity at the maximum in a Young's double slit experiment is I0. Distance between two slits is d=5λ, where λ is the wavelength of light used in the experiment. What will be the intensity in front of one of the slits on the screen placed at a distance D=10d ?

  • A
    I0
  • B
    I04
  • C
    34I0
  • Correct answer
    D
    I02

Solution

In YDSE Imax=I0

Path difference at a point in front of one of shifts is

∆x=dyD=dd2D=d22D     ( Here  y= d 2 )

∆x=d2210d=d20=5λ20=λ4

Path difference is

ϕ=2πλΔx=2πλλ4

ϕ=π2

So intensity at that point is

I=Imaxcos2θ2

I=I0cos2π4=I02

Hence, the correct answer is option: 'D'.

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