AP EAMCET202317 May 2023Morning ShiftPhysicsElectromagnetic WavesActual
The electric field in NC ⁻¹ of an electromagnetic wave is E =36 Sin ( t - kx ) . The average energy density of the electromagnetic wave due to the electric field is ( 1 4 ₀ =9 10^9 Nm ^2 C ⁻² )
Options
- A36 10⁻⁹ Jm ⁻³
- B18 10⁻⁹ Jm ⁻³
- C36 10⁻⁷ Jm ⁻³
- D18 10⁻⁷ Jm ⁻³
Correct answer
B. 18 10⁻⁹ Jm ⁻³
Step-by-step solution
The average encrgy density of the electromagnetic wave is given by aligned & U _ av = 1 2 ₀ E ^2 & = 1 2 8.86 10⁻¹² (36)^2 =18 10⁻⁹ ~J / m ^3 aligned