Is Electricity Generated when a Magnet Falls Through a Copper Pipe?

[Yoann]

The title is pretty self-explanatory. I know the speed of the falling magnet is much slower in a copper pipe, but since the magnetic field moves, is there still some electricity generated in the process, even though the speed isn't great?

Thanks!

 

[Rooted]

Yes, currents are produced and they are called ohmic currents. This may interest you

http://www.if.ufrgs.br/~levin/Pdfs.dir/AJP000815.pdf

 

[mrspeedybob]

The fact that current is produced is the reason that the magnet falls slower. the current produced by the moving magnetic field produces its own magnetic field that inhibits the motion of the falling magnet.

 

[Yoann]

Great, thanks for the replies. And Rooted, awesome document you have there!

So is the amount of current produced proportional to the size of the pipe and strength of the magnet? I'm guessing yes, right? Like if we plugged light bulbs to the copper pipe, the bigger the pipe and stronger the magnet, the more light bulbs would go on?

 

[mrspeedybob]

Great, thanks for the replies. And Rooted, awesome document you have there!

So is the amount of current produced proportional to the size of the pipe and strength of the magnet? I'm guessing yes, right? Like if we plugged light bulbs to the copper pipe, the bigger the pipe and stronger the magnet, the more light bulbs would go on?

To a point. You have to remember conservation of energy. If you drop a magnet through the tube under the influence of gravity the magnet starts with a given amount of gravitational potential energy. The stronger the magnet and the more conductive the tube the more energy will be converted into electricity and the less will be converted into kinetic energy and lost to friction.

 

[Yoann]

Ok I get it now. Thanks for the reply!

 

[FeynmanIsCool]

Eddy Currents!