Question

A EM wave in vacuum travels in the +x direction. At a moment in time, the magnetic field is −(9.20 ?T)?̂. Find the magnitude and direction of the electric field.

Answer 1

The direction of propagation of EM wave is along the +ve X – axis.

The magnetic field component of EM wave, B = – 9.20 x 10^-6 T k

The magnitude of the electric field, E = cB = 3 x 10⁸ x 9.20 x 10^-6 = 27.6 x 10² N/C = 2.76 x 10³ N/C

The direction of propagation of an EM wave is given by the cross product of E and B

Since, propagation is along the + x axis and magnetic field is along – ve Z axis, the electric field must be acting along -ve Y – axis ( i = - j x – k)

The direction of electric field is along -ve Y-axis.