Tue November 22, 2011 By:

Ina conductor placed in a magnetic field the current is induced only if the magnetic field changes with time,why?the magnetic field exerts force on free electrons to must happen also when field doesnot changes with time. so why do we need a changing magnetic field for current to be induced.

Expert Reply
Tue November 22, 2011
magnetic field exerts force on electrons( or charges)when the charge or any charge is in motion , or there is relative motion between electron/charge and magnetic field.
force  F=qv×B=qvB sin?
if v=0,F=0
so when the conductor moves in mag field or magnet moves near the conductor, then only electrons experience force.
As a whole the net velocity of all the electrons in a conductor is 0.
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