Question

A plane electromagnetic wave of frequency 25 MHZ travels in free space along the x-direction. At a particular point in space and time the electric vector is E = 6.3j V/m. Calculate B at this point.

Answer 1

Dear student
. The magnitude of B


$$\begin{gathered} B=\frac{E}{c} \\ B=\frac{6.3V/m}{3\times {10}^{8}m/s}=2.1\times {10}^{-8}T \end{gathered}$$

To find the direction, we note that E is along y-direction and the wave propagated along x-axis. Therefore, B should be in a direction perpendicular to both x-, and y-axes. Using vector algebra, E × B should be along x-direction. Since, (+ j ) × (+ k )= i , B is along the z-direction. Thus, B= $2.1\times {10}^{-8}$ T

Regards