AP EAMCET202119 Aug 2021Evening ShiftPhysicsElectromagnetic WavesActual
The magnetic field of a plane electromagnetic wave is given by B = ( 400 μT ) sin 4 . 0 x 10 15 s - 1 t - x c Average energy density corresponding to the electric field is
Options
- A8 × 10 − 3   J   m − 3
- B31.8 × 10 − 3 J   m − 3
- C80 × 10 − 3   J   m − 3
- D3.18 × 10 − 3   J   m − 3
Correct answer
B. 31.8 × 10 − 3 J   m − 3
Step-by-step solution
Average energy density, U avg = B 0 2 2 μ 0 ⇒ U avg = 400 × 10 - 6 2 2 × 4 π × 10 - 7 ⇒ U avg = 16 × 10 - 8 8 π × 10 - 7 ⇒ U avg = 63 . 66 × 10 - 3 Average energy density corresponding to electric field, U = U avg 2 = 63 . 66 × 10 - 3 2 ⇒ U = 31 . 8 × 10 - 3   J . m - 3