Physics Van 3-site Navigational Menu

Physics Van Navigational Menu

Q & A: conductive carbon fiber

Learn more physics!

Most recent answer: 05/21/2013
Q:
I'm trying to find out if carbon fiber could be used in coils, like copper, to create electricity. I understand that aluminium can be used as well but I don't know enough about induction to know if it would work. Is there something special about copper and aluminium that make them work in an electric generator? Thanks for taking the time to read this!
- Josh (age 34)
Roanoke VA
A:

The coils in those electromagnets have to conduct electricity. If they're made out of very good conductors, then they won't heat up too much from the electrical current. (The heating power is I2R, where I is the current and R is the resistance, which goes as 1/conductivity.) Metals are good conductors, and some (silver, copper, aluminum) are especially good. Plain carbon fibers can also conduct (see ) but not as well, so they would make poor magnet coil wires. I've read that some commercial carbon fibers have been treated with a coating that makes them very poor conductors.

Mike W. (posted without checking until Lee returns)


(published on 05/20/2013)

Follow-Up #1: conductivity and magnet wires

Q:
Thanks for that answer! I hadn't thought about the heat... So, it may be possible, just not nearly as efficient as the every day metal conductor. Perhaps, without the coating and maybe some chemical manipulation this would be a viable replacement for the pounds and pounds of copper that are currently used as coils. Any other input to this would be most welcome.
- Josh Oertle (age 34)
Roanoke VA
A:

That efficiency issue is a big deal. A good electrical motor is highly efficient. Using resistive wires would wreck that. For electromagnets, using very resistive wires would reduce the attainable fields to the point where the magnet would not be of much use. In order to get large fields sustainably, for example, MRI machines use superconducting wire, with zero resistance. Even copper wouldn't be nearly good enough.

Some carbon nanotubes can be great conductors on a microscopic scale. (see ) Getting them linked together into a usable wire is a tough engineering challenge.

Mike W.

(posted without checking until Lee returns)


(published on 05/21/2013)

Follow-up on this answer.