FIt is a magnet that can be turned on and off by turning a current on or off
i.Moving a conductor (or a coil) in a magnetic field induces a current / voltage.
ii.For a current to be induced we must have a closed circuit for the current to flow. Otherwise a voltage is induced.
iii.The direction of the induced current / voltage can be predicted using Fleming’s Right Hand Rule.
Where Does the Magnetic Energy Come From?
FA straight wire of length l is moved at right angles (with a velocity v) across a magnetic field of strength B. The wire will have an induced current I flowing through it and will thus experience a motor force on it given by F = B × I × L
FLenz’ Law states that the motor force will oppose the movement of the wire (i.e. the force will be in the opposite direction to the wire’s movement).
FThe rate at which mechanical work is being done (i.e. power) against the motor force is given by P = F × v = B × I × L × v
FWe have previously derived an expression for the e.m.f. induced across such a straight wire: F = B × L × v
FThe electrical power generated in the wire is then the product of the e.m.f. and the induced current : P = B × I × L × v = E × I