"Sal M. Onella" wrote
...

"Szczepan Bia³ek" wrote in message
...

snip

I am not interesting in theoretical physics.

Then perhaps this
http://www.mrdowling.com/images/701zeus.gif
is more what you're after.

(No, that's not Maxwell.)

If you like the theoretical physics try this:
http://www.df.lth.se/~snorkelf/Longitudinal/node4.html
S*