Question

The electric field in \( N C^{-1} \) of an electromagnetic wave is \( E = 36 \sqrt{\pi} \sin ( \omega t - kx) \). The average energy density of the electromagnetic wave due to the electric field is:

• A. \( 36 \times 10^9 \, J m^{-3} \)
• B. \( 18 \times 10^9 \, J m^{-3} \)
• C. \( 36 \times 10^7 \, J m^{-3} \)
• D. \( 18 \times 10^7 \, J m^{-3} \)

Hint:

For an electromagnetic wave, the energy density is proportional to the square of the electric field amplitude.

Answer 1

The Correct Option is B

The average energy density of an electromagnetic wave can be found using the formula for energy density, which is proportional to the square of the electric field. From the given electric field equation, we calculate the energy density. Thus, the correct answer is option (2).