January 12th in 1832 Michael Faraday did the following experiment in London:

He placed two copperplates in the Thames river at opposite ends of a bridge crossing at 300m apart. He then connected these copperplates with insulated wires to a voltage meter.
He measured a 19mV voltage. Magnetic field in London is measured to be 43µT (43*10^-6 T) and inclination is 71 degrees.

Why did Faraday's meter measure a voltage and what was the velocity of the water in the river Thames at that time?

(In reply to Answers by vswitchs)

Thanks for that info.

Re the rotation of the plates, I had that thought in mind, but I was also somewhat thinking that there might have been a difference due to a different orientation across the flux.  But you explanation is quite clear.

Posted by brianjn on 2006-10-22 21:17:48