Question

A circular loop of wire is rotated at constant angular speed about an axis whose direction can be varied. In a region where a uniform magnetic field points straight down, what must be the orientation of the loop's axis of rotation if the induced emf is to be zero?

Answer 1

here the coil must be oriented in such a way that its plane is perpendicular to the magnetic field

Step-by-step explanation:

As we know by Faraday's law of electromagnetic induction

Rate of change in magnetic flux will induce EMF in the coil

so here we will have

`EMF = (d\phi)/(dt)`

here we know that

`\phi = NB.A`

now if the magnetic flux will change with time then it will induce EMF in the coil

`EMF = N(d)/(dt)(B.A)`

so here induced EMF will be zero in the coil if the flux linked with the coil will remain constant

so here the coil must be oriented in such a way that its plane is perpendicular to the magnetic field

In such a way when coil will rotate then the flux linked with the coil will remains constant and there will be no induced EMF in it