A plane electromagnetic wave of frequency `25 Mhz` travels in free space along the x-direction. At a particular point in space and time, `E= (6.3 j) V//m`. What is `B` at this point?

Explanation

Using Eq. (8.10), the magnitude of B is
`B=(E)/(c)`
`=(6.3 V//m)/(3xx10^(8)m//s)=2.1xx10^(-8)T`
To find the direction, we note that E is along y-direction and the wave propagate along x-axis. Therefore B should be in a direction perpendicular to both x--and y-axes. Using vector algebra, `ExxB` should be along x-direction since, `(+hatj)xx(+hatK)=hati`, B is along the z-direction
Thus, `B=2.1xx10^(-8)kT`