AC on the third rail

[Dutchrailnut]

Even AC propulsion does not run of AC power directly, on AC propulsion power gets rectified first.

 then inverters are fed of the DC busbar.

High voltage AC is normally banned from anywhere within human reach.

[carnej1]

aegrotatio

 I haven't read the book on Sprague but I intend to soon, but what's the reason AC is not used on the third rail, and has it ever been used on the third rail?  What about AC at lower voltages?  Physics?

Thanks.

while I am no expert on rail electrification, I know there are many subway systems running with AC traction motors so it is very doable..

[aegrotatio]

 I haven't read the book on Sprague but I intend to soon, but what's the reason AC is not used on the third rail, and has it ever been used on the third rail?  What about AC at lower voltages?  Physics?

Thanks.