Question

A sinusoidal electromagnetic wave has an average intensity of I1 =100 W/m2. By what factor would the electric-field amplitude of the wave have to be increased in order for the wave to have an average intensity of I2 = 8100 W/m2 ?

Answer 1

Answer:

9

Explanation:

Given,

Intensity,I₁ = 100 W/m²

Intensity, I₂ = 8100 W/m²

We know,

Intensity is directly proportional to Square of Amplitude.

$\dfrac{A_2}{A_1}=\sqrt{\dfrac{I_2}{I_1}}$

   $\dfrac{A_2}{A_1}=\sqrt{\dfrac{8100}{100}}$

    $\dfrac{A_2}{A_1}=\sqrt{81}$

   $\dfrac{A_2}{A_1}=9$

Factor the electric-field amplitude increased is equal by factor  9.