E.m.f. induced in a straight conductor
When a straight conductor is
moved through a magnetic field an e.m.f. is induced between its ends. This movement must
be in such a direction that the conductor cuts through the lines of magnetic flux, and will be a
maximum when it moves at right angles to the field (Figure 1(a)).
Let the length of the conductor be L and the flux density of the
field be B.
If the conductor moves with velocity v at right angles to the field then the flux
cut per second will be BvL (since the conductor will sweep out an area vL every
second).
But the rate of cutting flux is equal to the e.m.f. induced in the conductor.
Therefore
If the conductor cuts
through the flux at an angle
q ((b) in Figure 1), where
q is the angle between the magnetic field and the direction of motion, the equation
becomes
You can see that the maximum e.m.f is generated when the conductor
moves at right angles to the field. (
q = 90
o and so sin
q = sin90 = 1).
