The intensity at the central maximum of a double-slit interference pattern is 4I_1. The intensity at the first minimum is zero. at what fraction of the distance from the central maximum to the first minimum is the intensity I_1? Thank you.

y = 60λL/πd

Explanation:

To find the distance you can use the expression for the intensity of the fringes in a Young's experiment:

d: distance between the slits

L: distance to the screen

y: height of the ring

λ: wavelength of light

For the first maximum you have that I=4I_1, thus, for y=0 (central maximum):

=I_o

to know what is the distance from the central maximum (y=0) you can do y the subject of the formula and replace I=I_1:

hence, the distance in which he intensity is I1 is 60λL/πd

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