Question

Two beams of light having intensities I and 41 interfere to produce a fringe pattern on a screen. The phase difference between the two beams are π/2 and π/3 at points A and B respectively. The difference between the resultant intensities at the two points is xl. The value of x will be ______.

Options

• 1

• 2

• 3

• 4

Answer 1

Two beams of light having intensities I and 41 interfere to produce a fringe pattern on a screen. The phase difference between the two beams are π/2 and π/3 at points A and B respectively. The difference between the resultant intensities at the two points is xl. The value of x will be 2.

Explanation:

I_A = I + 4I + 2`sqrt"I" sqrt(4"I")` cos `pi/2`

I_A = 5I

and I_B = I + 4I + 2`sqrt"I" sqrt(4"I")  `cos`pi/3`

= 5I + 2I = 7I

I_B - I_A = 2I