Question
Light is an electromagnetic wave composed of 2 oscillating fields, an electric field and a magnetic field, where the field equations are solutions to the wave equation. If an EM wave propagates along the x-axis such that the electric field oscillates along the z-axis and the magnetic field oscillates along the y- axis, respectively, with constants defined as such: If a radio wave (108 Hz) has a peak electric field value of 120 VAn, write down the field equations for the electric and magnetic fields (with values for the constants plugged in).
Explanation / Answer
w= 2pif = 2*3.14*10^8 = 6.28 *10^8
V = Lf, L = 3e8/10^8 = 3 m
K = 2pi/L = 2*3.14/3 = 2.1
E = 120 sin ( 2.1x -6.28*10^8)
now B = magnetic field
equation B = E/c
E = 120 sin ( 2.1x -6.28*10^8)/3e8
E = 4*10^-7sin ( 2.1x -6.28*10^8)