Question

The magnetic field in a plane electromagnetic wave is given by
$B=\left(200\mu T\right)\sin \left[\right(4.0\times {10}^{15}{s}^{-1}\left)\right(t-\frac{x}{c}\left)\right]$
Find the maximum electric field and the average energy density corresponding to the electric field.

Answer 1

Here $B=\left(200\mu T\right)\sin \left[\right(4\times {10}^{15}{s}^{-1}\left)\right(t-\frac{x}{c}\left)\right]\left(a\right)B_c=c\times B_0=200\times {10}^{-6}\times 3\times {10}^8=6\times {10}^4$
(b) Average energy density
$=\frac{1}{2{\mu }_0}{B}_0^2=\frac{(200\times {10}^{-6}{)}^2}{2\times 4\pi \times {10}^{-7}}=\frac{4\times {10}^{-8}}{8\pi \times {10}^{-7}}=\frac{1}{20\pi }=0.0159\approx 0.016j/m^3$