Question

A plane electromagnetic wave of frequency 20 MHz travels through a space along x direction. If the electric field vector at a certain point in space is 6 V $m^{-1}$, what is the magnetic field vector at that point?

• A. $2\times {10}^{-8}T$
• B. $\frac{1}{2}\times {10}^{-8}T$
• C. $2T$
• D. $\frac{1}{2}T$

Answer 1

The correct option is A $2\times {10}^{-8}T$

Velocity of EM wave $v=3\times {10}^8$ $m/s$

Electric field vector $E=6$ $V/m$

Thus magnetic field vector $B=\frac{E}{v}$

$\therefore$ $B=\frac{6}{3\times {10}^8}=2\times {10}^{-8}$ $T$