# A plane Electro magnetic wave of frequency $30\; MHZ$ travels in free space component of wave at a point $E= 6V/m$ along y direction . The magnetic field component B at this point would be

$(a)\;2 \times 10^{-8}\;T\;along\;z\;direction\\ (b)\;6 \times 10^{-8}\;T\;along\;x\;direction \\(c)\;2 \times 10^{-8}\;T\;along\;y\;direction\\(d)\;6 \times 10^{-8}\;T\;along\;z\;direction$

Magnetic compount $B= \large\frac{E}{c}$
Where $c$ is velocity of light .
$B= \large\frac{6}{3 \times 10^8}$$=2 \times 10^{-8}$
The wave propagates along x direction ,electric field is along y direction ,then magnetic field is along z direction.
Hence a is the correct answer.

answered Mar 24, 2014 by
edited Oct 8, 2014