If you have an electromagnet, made up of a solenoid and iron core...?

Question

What happens to the magnetic field and force of an electromagnet if no current is passing through the solenoid/wire? Will the iron core itself still produce a magnetic force? My resources tell me that the charged solenoid causes the domains in the iron core to line up (which makes it magnetic). Does that mean that if the solenoid is no longer charged, the iron core isn't as well? Help me out here, and I will appreciate it.

Answer 1

The resources you are talking of tells about the iron core but generally it depends on whether the material inside the solenoid is ferro- or para-magnetic. A paramagnetic substance retains the magnetization even after discharging the solenoid but a paramagnetic substance retains the magnetization only as long as the current is flowing through the solenoid.

Answer 2

The iron core of a solenoid is non-magnetic with no current flowing through the coil..

A solenoid valve, for example, is used when the cut off of flow is required.

Take an automatic washing machine. Electrical energy is used to energise the solenoid and open the water intake valve.

When the the water reaches the designated level, an automatic switch shuts off the power to the solenoid and closes the valve.
The washer goes into its next step in the timer sequence.

If the solenoid remained magnetic the valve wouldn't close.

Answer 3

The materials of cores of electromagnets and solonoids are carefully choosen NOT to hold magnetism when off as a tendency to hold magnetism would fight with the desire to magnetize quickly and release. Even more so with transformers which are made thin flat plates to fight the tendency as well as eddy currents that would form as the field reversed 60 times a second.

Answer 4

You said so.