Question

The wavelength of light used in young.'s double slit experiment is λ. The intensity at a point on the screen is I where the path difference is λ/6. If I₀ denotes the maximum intensity, then the ratio of I and I₀ is ______.

Options

• 0.866

• 0.5

• 0.707

• 0.75

Answer 1

The wavelength of light used in young.'s double slit experiment is λ. The intensity at a point on the screen is I where the path difference is λ/6. If I₀ denotes the maximum intensity, then the ratio of I and I₀ is 0.75.

Explanation:

Phase difference `phi = (2pi)/lambda xx "path difference"`

`= (2pi)/lambda xx lambda/6 = pi/3 = 60^circ`

Intensity, I = `"I"_"o" cos^2 (phi//2)`

`"I"/"I"_"o" = cos^2 (30^circ)`

`=> "I"/"I"_"o" = (sqrt3//2)^2`

`= 3/4 = 0.75`