Question

Problem 25.25

Part A

What is the electric field amplitude of an electromagnetic wave whose magnetic field amplitude is 2.9mT ?

Answer 1

In Harmonic electromagnetc wave a direct relationship between electric and magnetic field exists.

Electromagnetic Wave Propagation

E=E_mcos(kx-wt)

B=B_mcos(kx-wt)
integrating Electric field with x and magnetic field with time yields
dE/dx=-kE_msin(kx-wt)

dB/dt=wB_msin(kx-wt)

Maxwells 3^rd equation leads to
dE/dx=-dB/dt
=>kE_m=wB_m or B_m=E_m/c
Magnetic field amplitude is 2.9mT
So, E_m=B_m*c=2.9*10^-3*3*10⁸=870000v/m or 87*10⁴v/m