B field inside solenoid as a result of iron rod

[CAF123]

Homework Statement

Consider a solenoid with a time varying current and with a coil of wire placed around it. Suppose there is a soft iron rod inside the solenoid. My question is: What happens to the (induced) current in the coil of wire as a result?

Homework Equations

Faraday, magnetic flux,

The Attempt at a Solution

Since iron is ferromagnetic, (it has associated with it a permanent magnetic dipole moment), it gives out a net B field. So the B field inside the solenoid is increased. Since $$\phi_B = BA,$$ the magnetic flux then increases and hence the induced emf in the wire by Faraday. This causes the induced current to increase also.

Is this okay?

Many thanks.

 

[barryj]

Looks good.