Geometrical OpticsHard

Question

In a double slit experiment instead of talking slits of equal widths, one slits is made twice as wide as the other, then in the interference pattern

Options

A.the intensities of both maxima and the minima increase
B.the intensity of the maxima increases and the minima has zero intensity
C.the intensity of maxima decreases and the of minima increases
D.the intensity of maxima decreases and the minima has zero intensity

Solution

In interference we know that
     Imax = (√I1 + √I2)2) and Imin = (√I1 ~ √I2)2)2
Under normal conditions (when the widths of both the slits are equal)
    I1 I2 and I2 = ηI
∴ Imax = 4I and Imin = 0
When the width of one of the slit is increased. Intensity due to it that sliti would increase, while that of the other will remain same. So, let :
I1 = 1 and I2 = ηI     (η > 1)
Then, Imin = I(+√η)2η > 4I
and Imin = I(√η - 1)2 > 0
∴ Intensity of both maximum and minima is increased.

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