Question

Light waves from two coherent sources arrive at two points on a screen with path differences of 0 and /2. Find the ratio of intensities at these points.

Answer 1

Hello there,

● Answer -
I1 : I2 = 2 : 1

● Explaination -
# Given -
θ1 = 0 rad
θ2 = π/2 rad

# Solution -
Let I be intensity of each coherent source.

Intensity for path difference θ1 = 0 rad,
I1 = 2I (1 + cosθ1)
I1 = 2I (1 + cos0)
I1 = 2I (1 + 1)
I1 = 4I

Intensity for path difference θ2 = π/2 rad,
I2 = 2I (1 + cosθ2)
I2 = 2I (1 + cos90)
I2 = 2I (1 + 0)
I2 = 2I

Ratio of these intensities -
I1 / I2 = 4I / 2I
I1 / I2 = 2

Therefore, ratio of intensities is 2:1.

Hope this helps you...