Question

Differentiate between bar magnet and electromagnet

Answer 1

Hint: A bar magnet is a permanent magnet that has its own magnetic field and in the presence of electric current from a source, an electromagnet is a temporary magnet that generates a magnetic field. A magnet is a material capable of generating a magnetic field. It is invisible to the magnetic field. For making bar magnets, ferromagnetic materials can be used.

Complete solution:
Bar magnets:
These are made of magnetite-called naturally occurring minerals. These magnets are able to attract any ferromagnetic material (e.g. iron) and are magnetized permanently. It is not possible to turn their magnetic field on or off. They are weak magnets and their strength usually decreases with time. Their magnetic field strength cannot be varied. Their magnetic field lines are from the north pole and point towards the south pole, and they have fixed poles. It is not possible to reverse their polarity.

Electromagnets:
They are magnets that are man-made. When a wire carrying a current is wrapped around a piece of iron, the current generates a magnetic field around the wire and magnetizes the piece of iron. These magnets are temporary magnets, and when the current supply is turned on or off, their magnetic field can be turned on or off. It is also possible to vary their magnetic strength according to the need and they can produce very strong magnetic fields. Their poles are not fixed, so by changing the direction of current flow, their polarity can also be changed from the north pole to the south pole or vice versa.

Note:
Bar magnets are used in the manufacture of credit and debit cards, magnetic needles or compasses, and electromagnets are used in the manufacture of telephones, loud speakers, stereos, etc. An electromagnet whose magnetic strength can be varied by increasing or decreasing the number of turns of the current carrying coil is an instance of a solenoid.