MadSci Network: Physics

Re: Electromagnet field strength vs current

Date: Mon Jun 16 10:33:43 2003
Posted By: Dr. Fred Jeffers, Staff, Magnetic Recording Research, Iomega corp.
Area of science: Physics
ID: 1055769808.Ph

     Good question!  Any real magnetic material has parameter specifying 
its "magnetic hardness" called the coercivity.  The field applied must be 
larger than the coercivity in order to magnetize it very much.  The field 
is given by 

                   H = 4 Pi N I/(10L)

where N is the number of turns, I is the corrent in Amps, and L is the 
length of the coil in cm.  With N = 100 and L = 12 cm the field is about 
10 Oe.  This is about right for the coercivity of a "soft" iron rod.  Try 
a big nail.  It may have a lower coercivity than the rod you are using.  
You can get them at any hardware store.   

Current Queue | Current Queue for Physics | Physics archives

Try the links in the MadSci Library for more information on Physics.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-2003. All rights reserved.