In a Young's double slit experiment, using unequal slit widths, the intensity at a point midway between a bright and dark fringes is 4I. If one slit is covered by an opaque film, intensity at that point becomes 2I. If the other is covered instead, then the intensity at that point is

Options

A. `2I`
B. `5I`
C. `(5+2sqrt(2))I`
D. `(5+4sqrt(2))I`

Answer

A

Explanation

Location of the point `y=omega/4=(lambdaD)/(4d)`
`rArr Deltax=(yd)/D=lambda/4`
`rArr phi=(2pi)/lambda.Deltax=pi/2`
`because I_(R)=I_(1)+I_(2)+2sqrt(I_(1)I_(2))cosphi`
`:. 4I=2I+I_(2)+0`
`rArr I_(2)=2I`