AP EAMCET201822 Apr 2018Morning ShiftPhysicsElectromagnetic WavesActual
In a plane electromagnetic wave, the electric field oscillates with a frequency 2 10¹⁰ ~s ⁻¹ and amplitude 40 Vm ⁻¹ , then the energy density due to electric field is ( ₀=8.85 10⁻¹² Fm ⁻¹ )
Options
- A1.52 10⁻⁹ Jm ⁻³
- B2.54 10⁻¹⁹ Jm ⁻³
- C3.54 10⁻⁹ Jm ⁻³
- D4.56 10⁻⁹ Jm ⁻³
Correct answer
C. 3.54 10⁻⁹ Jm ⁻³
Step-by-step solution
Energy density due to electric field is aligned U & = 1 2 ₀ E^2 Here, E & = E₀ 2 = 40 2 U & = 1 2 8.85 10⁻¹² 40 40 2 & =3.54 10⁻⁹ ~J / m ^3 aligned