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They are microscopic electric currents, which, in the case of ferromagnetism, are created through certain electrons rotating around themselves in the material (electron spins).

Electron spin can be viewed as a microscopic small circulating current.

Strengths of permanent and electromagnets

The strength of a magnetic field of an electromagnet depends on the core material, the number of solenoid windings and the intensity of the current.

With a high enough amperage, the electromagnet can develop a significantly stronger magnetic field than a permanent magnet.

The strength of the electromagnet factors

Left: A permanent magnet with field lines

Right: An electromagnet with the power source (left), solenoid (orange) and soft-iron core (middle)

Soft-iron core (grey) with the coil (orange)

Soft-iron core

When it comes to electromagnets, usually a soft-iron core is placed in the coil, which considerably strengthens its magnetic field, because the magnetic field of the coil magnetizes the soft-iron core and, thereby, creates an additional magnet.

The soft-iron core loses its magnetization after the current is turned off.

This is desirable in order to be able to turn the magnet on and off.

Magnetically soft and hard iron

The term magnetically "soft" is based on the fact that mechanically soft iron loses its magnetization, while the mechanically hard iron (steel) that is carbon-enriched keeps part of its magnetization.

This is called remanence.

The Latin word "remanence" means "to remain".

Material with high remanence is referred to as "magnetically hard".

Solenoids with a current flow magnetize also permanent magnets, like our super magnets, which are all made of magnetically hard material.

Electromagnets

A wire with an electric current (charged electrons) produces a magnetic field in its surroundings.

The strength of the magnetic field depends on the intensity of the current and the shape of the wire.

Each wire with a current flow is practically an electromagnet.

The orange arrow indicates the technical direction of the current.

Historically, it is the opposite of the direction of the electrons.

If you bend the wire with the current flow into a circle, it creates a magnetic field with poles.

Therefore, a circulating current creates a magnet with a north and south pole.

In common magnets, the wire is often wound into a multi-layered coil, which is also called a solenoid.

A wire coil with north and south pole

Bar Magnets and Electromagnets

An electromagnet works on the principle that an electric current allows electrons to flow in a circuit.

Bar magnet is a permanent magnet which is always magnetized; Electromagnet is a conductor

Electromagnet Science

Build an Electromagnet

If you have ever played with a really powerful magnet, you have probably noticed one problem.

You have to be pretty strong to separate the magnets again! Today, we have many uses for powerful magnets, but they wouldn’t be any good to us if we were not able to make them release the objects that they attract.

In 1820, a Danish physicist, Hans Christian Oersted, discovered that there was a relationship between electricity and magnetism.

Thanks to Oersted and a few others, by using electricity, we can now make huge magnets.

We can also cause them to release their objects.

Electricity and magnetism are closely related.

The movement of electrons causes both, and every electric current has its own magnetic field.

This magnetic force in electricity can be used to make powerful electromagnets that can be turned on and off with the flick of a switch.

But how do you make an electromagnet?

By simply wrapping wire that has an electrical current running through it around a nail, you can make an electromagnet.

When the electric current moves through a wire, it makes a magnetic field.

If you coil the wire around and around, it will make the magnetic force stronger, but it will still be pretty weak.

Putting a piece of iron or steel inside the coil makes the magnet strong enough to attract objects.

The strength of an electromagnet can be increased by increasing the number of loops of wire around the iron core and by increasing the current or voltage.

You can make a temporary magnet by stroking a piece of iron or steel (such as a needle) along a permanent magnet.

There is another way that uses electricity to make a temporary magnet, called an electromagnet.

Let's build one!

You’ll need: An iron or steel bolt

24 inches of insulated wire

2 D-cell batteries with holders

Alligator clips or tape to hold the wire connections together

Some paper clips or other magnetic items

A journal or paper to take notes and respond to questions

Directions:

1. Wrap the wire in a tight, even coil around the bolt.

Leave 3 or 4 inches of wire loose at each end.

Keep wrapping the wire until you get to the end of the bolt.

There may be as many as 3 or 4 layers of wire all the way up and down the bolt.

Your electromagnet should look something like this:

2. Attach one end of the wire to the positive (+) end of one of your batteries.

Attach the other end of the wire to the negative end (-) of your battery pack.

3. Try to pick up one of the paper clips with your electromagnet.

What happens? Now, unhook one of the wires from the battery.

Will your electromagnet pick up a paper clip now? What do you need flowing through the wire to make the iron bolt act like a magnet?

4. How many paper clips will your electromagnet hold? Can you hang clips on both ends of the bolt? Why?

5. How can you make your electromagnet stronger? Try adding more batteries to your battery pack.

Make sure all the batteries “face” the same direction in the circuit.

Now, how many paper clips will your electromagnet hold?

6. How is the strength of the electromagnet affected by the increase in electricity traveling through the wire?

7. After using the electromagnet, remove the iron nail or bolt.

Can the nail still pick things up? How many paper clips or staples can it pick up? Try dropping the nail or bolt a couple of times on the floor.

How does this affect whether or not you can pick up any paper clips or staples? How many paper clips or staples can the nail or bolt pick up after being dropped?

Be sure to disconnect your electromagnet when it is not in use.

Leaving the wires connected will drain your battery.

The key difference between bar magnet and electromagnet is that the bar magnet has a permanent magnetic field whereas the electromagnet has a temporary magnetic field.

A magnet is a material that can produce a magnetic field.

The magnetic field is invisible.

But, it can produce a force that pulls on other ferromagnetic materials such as iron.

Also, it can either attract or repel other magnets.

Furthermore, there are two major types of magnets as permanent and temporary magnets.

A bar magnet is a good example of a permanent magnet whereas an electromagnet is an example of a temporary one.

What is a Bar Magnet?

A bar magnet is a permanent magnet that can create its own persistent magnetic field.

The lines of the magnetic field of this magnet form closed lines.

Above all, the field direction is outward from the north pole and goes into the south pole of the magnet.

Ferromagnetic materials can be used to make bar magnets.

A Bar Magnet

The magnetic field is strongest inside the magnet.

When considering the external magnetic field, the strongest is near the poles.

The north pole of one magnet can attract the south pole of another magnet.

However, the north pole repels the north pole of another magnet and vice versa.

We can easily trace out the magnetic field lines of these magnets using a compass.

The needle of the compass rotates until it lines up with the magnetic field lines of the magnet.

What is an Electromagnet?

An electromagnet is a type of temporary magnet that can produce a magnetic field in the presence of an electric current.

It is temporary because the magnetic field disappears when we turn off the electric current.

Also, these magnets typically contain a wire wound to into a coil.

Here, the current that passes through the wire creates a magnetic field.

An Electromagnet

And, this magnetic field is concentrated in the hole in the center of the wound coil.

Often, the coil is wound surrounding a magnetic core.

Also, this magnetic core is a ferromagnetic material.

Therefore, it can produce a strong magnetic field.

The main advantage of this type of magnets is that we can quickly change the magnetic field by controlling the electric current that passes through the wire.

However, one disadvantage is that this needs a continuous power supply to maintain the magnetic field.

What is the Difference Between Bar Magnet and Electromagnet?

A bar magnet is a permanent magnet that can create its own persistent magnetic field whereas an electromagnet is a type of temporary magnet that can produce a magnetic field in the presence of an electric current.

Therefore, the key difference between bar magnet and electromagnet is that the bar magnet has a permanent magnetic field whereas electromagnets have a temporary magnetic field.

Furthermore, we cannot change the magnetic field of a bar magnet quickly as we wish but with electromagnets, it is possible by controlling the electric current that passes through the wire.

So, this also a difference between the bar magnet and electromagnet.

Moreover, we can use a bar magnet as it is but the electromagnets always need a power supply to create the magnetic field.

Further facts about the difference between bar magnet and electromagnet is shown in the below infographic.

Summary – Bar Magnet vs Electromagnet

Both bar magnets and electromagnets are common types of magnets that can attract or repel things.

The key difference between bar magnet and electromagnet is that the bar magnet has a permanent magnetic field whereas the electromagnet has a temporary magnetic field.

Difference Between Electromagnet and Permanent Magnet

Electromagnet

The magnetic properties are displayed when current is passed through it

Magnetic properties exist when the material is magnetized

The strength is adjusted depending upon the amount of flow of current

The strength depends upon the nature of the material used in its creation

Removal of magnetic properties is temporary

Once magnetic properties is lost, it becomes useless

It requires a continuous supply of electricity to maintain its magnetic field.

It doesn’t require a continuous supply of electricity to maintain its magnetic field

It is usually made of soft materials

It is usually made of hard materials

The poles of this kind of magnet can be altered with the flow of current

The poles of this kind of magnet cannot be changed.

These were some difference between the electromagnet and permanent magnet.

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