Question

Two sinusoidal plane waves of the same frequency having intensities I₀ and 4I₀ are travelling in the same direction. The resultant intensity at a point at which waves meet with a phase difference of zero radians is ______

Options

• I₀

• 5I₀

• 9I₀

• 3I₀

Answer 1

Two sinusoidal plane waves of the same frequency having intensities I₀ and 4I₀ are travelling in the same direction. The resultant intensity at a point at which waves meet with a phase difference of zero radians is 9I₀.

Explanation:

`"I"_1 = "I"_0, "I"_2 = 4"I"_0, alpha = 0` rad

Resultant intensity I = I₁ + I₂ + `2sqrt("I"_1"I"_2)` cos 0°

= `"I"_0 + 4"I"_0 + 2sqrt("I"_0 xx 4"I"_0) xx 1`

= 5I₀ + 4I₀

= 9I₀