Question

Two coherent monochromatic light beam of intensities I and 4I are super imposed. The max .and min. possible intensities in the resulting beam are

Options

• 5 I and I

• 9 I and I

• 5 I and 3 I

• 9 I and 3 I

Answer 1

9 I and I

Explanation:

I₁ = I₁, I₂ = 4I, `I_1/I_2 = a_2/b_2 = I/(4I) = 1/4`

`a/b = 1/2` or b = 2a

`I_(max)/I_(min) = (a + b)^2/(a - b)^2 = (9a^2)/a = 9/1`

I_max = 9 I and I_min = I