Peak Velocity

As the EM wave propagates, the peak depth moves as a function of time. The velocity at which the peak moves is called the peak velocity. By by taking time derivative of the peak distance and setting it to zero, the peak velocity is given by:

\[v_{max} = \frac{d z_{max}}{dt} = \frac{1}{\sqrt{2\mu\sigma t}}\]

Fig. 56 Electric field as a function of time 100 m from a 1D impulse in the field in a 0.01 S/m whole space (a). Electric field at t = 0.03 ms as a function of distance (Modifed from [WH88]) (b).