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Copper Rod on Two Rails?
A copper rod of mass 0.7 kg rests on two rails 0.7 m apart and carries a current of 31 A from one rail to the other. The coefficient of static friction is 0.8. What is the magnitude of the least magnetic field that would cause the bar to slide?
1 Answer
- ?Lv 74 years ago
The friction force that is to be overcome is
F = mu m g
The magnetic force is
F = B I L
So
B I L > mu m g
B > (mu m g )/(I L)
B > (0.8 * 0.7kg * 9.8N/kg) / ( 31A * 0.7m)
B > 0.25 T
