Peak time calculation not right in TDEM_Planewave_Wholespace app

[jiajiasun]

Hi,

I was using the app TDEM_Planewave_Wholespace.ipynb to explore the peak time. I set conductivity to 1 S/m. And adjust the time to see when the peak reaches the depth of 400 m.

The app shows that it takes about 0.1 s for the peak to arrive at 400 m depth.

I also used the equation $t_{max} = \frac{\mu\sigma z^2}{6}$ to calculate the peak time, which is $t_{max} = 4 \pi 10^{-7} X 1 X400^2/6=0.0335 s, which is quite differnt from what the app shows.

Could anyone please explain what was going on here? Thanks!