What is an Electromagnet?
Magnet is considered cool as all kinds of fun experiments can be done with their help, but the usefulness of magnet is limited. The magnet always attracts, which is sometimes needed like in a fridge. However, the usage of electromagnets changes that, and the application becomes endless.
A magnet that is created by using the electric current created by electricity is known as the electromagnet. Similarly, an electromagnet can be turned on or off to electricity. Accordingly, its strength can be increased or decreased by strengthening or diminishing the current.
A simple electromagnet can be created with the help of a coil of wire wrapped around an iron core. A core of ferromagnetic material like iron, which serves to increase the magnetic field created. The amount of current through the winding is proportional to the amount of magnetic field generated.
The magnetic field is produced by the coil of wire, also known as a solenoid. The above drawing shows the cross-section through the center of the coil. The crosses are the wires through which the current moves into the page. Here the dots are the wires through which current is moving up out of the diagram.
Electromagnet Definition
The magnetic field, produced with the flow of an electric current in a magnet, is known as the electromagnet.
It usually consists of a wire wound in a coil, and the current through the wire creates the magnetic field, which is concentrated in the hole, representing the center of the coil. As soon as the current turns off, the magnetic field disappears. The magnetic core around the coil of wire is made of ferromagnetic or ferromagnetic material; for example, iron. The magnetic core strengthens the magnetic flux and makes more powerful magnets.
An electromagnet functions because an electric current generates a magnetic field and the magnetic field generated by an electric current forms circle around the electric current, as shown in the diagram below.
An electromagnet functions because an electric current generates a magnetic field. The magnetic field produced by electric current forms circles around the electric current, as shown in the diagram below:
The primary advantage of an electromagnet over a permanent magnet is that the magnetic field's strength can be monitored by controlling the amount of electricity in the winding. However, compared to a permanent magnet that does not need any power, electromagnet requires a constant supply of current to provide the magnetic field.
How is an Electromagnet Made?
When charges like protons and electrons are stationary, electric forces are created like an attractive or repulsive force between the charged particle. When they move, they produce magnetic forces either a repulsive or attractive force between the charged particles due to the motion. Within a magnet, a lot of particles are moving and generate the magnetic field for the magnet.
Electromagnets generally made from a wire; a wire curled into a series of turns. Strengthens and concentrates the magnetic field more than a single stretch of wire. The wire turns are coiled around an ordinary magnet. Since it is made of ferromagnetic material like iron, it makes the electromagnet more powerful.
The Electromagnet Can Be Made Sturdier By Doing the Following Things.
Draping the coil around a piece of iron (such as an iron nail)
Increasing the number of turns to the coil
Increasing the current flowing through the coil
Due to the resistance of the wire, causing heat, there is a limitation to the quantity of current to pass safely through the wire.
This knowledge of magnetism work is essential because it gives us the ability to create electromagnets. The flow of electrons through a circuit is known as electricity, so an electrical wire produces a magnetic field just like a magnet.
How Electromagnet Works?
To describe how can this principle be utilized to make an electromagnet, consider the below working in brief.
When the electric current passes through a straight wire, it creates a magnetic current all around it. We can create a magnetic field intensity by winding copper wire in a certain direction. If we want to further increase the intensity, we should do multiple windings of the copper wire. However, we need to pay attention as not to wind it in the opposite direction since this will cancel the effect of previous winding. We should do a straight line of one winding direction to another; starting from the end of the winding to multiple windings.
Inside the iron material, each atom acts as a natural magnet since they are in random orientation, the effect of the tiny magnet cancels each other. However, when iron is coiled inside the copper wire winding, the entire tiny magnet inside the winding core will align itself in the direction of the magnetic field. Hence the effect of the electromagnet will be much stronger.
The strength of the magnetic field is also affected by the magnitude of the current passing through it to a saturation point where there is no atom/ion left in the core not aligned with the magnetic field. Also by stopping current flow through an electromagnet, we can remove the magnetism effect on the core and in the wires.
The biggest advantage of the electromagnet is that they can be polarized and changed just by reversing the poles' directions. This gives us the biggest pros while building electric generators or motors. The priority of an electromagnet can be identified here.
We use the right-hand rule to do that. When we grip the ball with the right-hand thumb, the four fingers holding the flow will show the direction of current and the thumb shows magnetic north. If we change the direction of the flow, the gripping of the right-hand rule will be as shown.
Notice that the four fingers will also show the direction in this position and magnetism south becomes magnetic north.
FAQs on Electromagnets
1. What is an electromagnet and how does it work?
An electromagnet is a temporary magnet created when an electric current flows through a coil of wire. Its working principle is based on the fact that electricity produces a magnetic field. Typically, a wire is wound around a core made of a ferromagnetic material like soft iron. When current passes through this coil (known as a solenoid), it generates a magnetic field. This field can be switched on or off simply by controlling the flow of current.
2. What are the main differences between an electromagnet and a permanent magnet?
The key differences between an electromagnet and a permanent magnet are:
- Source of Magnetism: An electromagnet's magnetic field is produced by an external electric current. A permanent magnet has an intrinsic magnetic field from its internal atomic structure.
- Control: The strength of an electromagnet can be easily changed by varying the current, and it can be turned on or off. A permanent magnet has a fixed strength and is always 'on'.
- Core Material: Electromagnets use soft iron cores that magnetise and demagnetise easily, while permanent magnets are made of materials like steel or neodymium alloys that retain magnetism.
3. What factors determine the strength of an electromagnet?
The strength of a typical solenoid-type electromagnet is determined by three main factors:
- Amount of Current: Increasing the electric current flowing through the coil results in a stronger magnetic field.
- Number of Coils: Winding more turns of wire around the core concentrates the magnetic field, significantly increasing its strength.
- Core Material: Inserting a soft iron core inside the coil dramatically boosts the magnetic strength because the core itself becomes strongly magnetised.
4. What are some important applications of electromagnets in everyday technology?
Electromagnets are crucial components in a wide range of devices. Some important real-world examples include:
- Electric Motors and Generators: They use the interaction between magnets and current-carrying coils to create motion or generate electricity.
- Loudspeakers and Headphones: An electromagnet attached to a cone vibrates to produce sound waves.
- Scrapyard Cranes: Massive electromagnets are used to lift and transport heavy iron and steel scrap.
- Electric Bells and Relays: They use an electromagnet to create a mechanism that makes or breaks a circuit.
- Medical Imaging (MRI): Extremely powerful superconducting electromagnets are used to create detailed images of the inside of the body.
5. Why is a soft iron core preferred over a steel core for making an electromagnet?
A soft iron core is preferred because it has high magnetic permeability and low retentivity. This means it can be very easily magnetised to create a strong field when the current is on, but it also loses its magnetism almost completely the moment the current is turned off. Steel, in contrast, has high retentivity and would remain magnetised, effectively becoming a permanent magnet. This would defeat the primary advantage of an electromagnet: its ability to be controlled.
6. How does an electromagnet behave when connected to an Alternating Current (AC) source?
When an electromagnet is powered by AC, its magnetic field continuously and rapidly changes. Since the AC current reverses its direction periodically, the North and South poles of the electromagnet also flip back and forth at the same frequency as the current. This property is essential for devices like transformers and AC motors but is unsuitable for applications needing a constant magnetic pull, for which Direct Current (DC) is used.
7. Can the strength of an electromagnet be increased forever by increasing the current?
No, the strength cannot be increased indefinitely. While increasing the current initially increases the magnetic field strength, the ferromagnetic core eventually reaches a point called magnetic saturation. At this point, all the magnetic domains within the core material are aligned, and it cannot become any more magnetised. Further increases in current will only produce a negligible increase in the overall magnetic field strength.
8. How do electromagnets provide a clear example of the link between electricity and magnetism?
Electromagnets are a perfect practical demonstration of electromagnetism, the fundamental principle that electricity and magnetism are interconnected. They show that a magnetic field can be generated and controlled purely by the flow of electric charges (current). The ability to produce a powerful magnetic force simply by running a current through a wire, and to make that force disappear by stopping the current, is direct proof that these two forces are different aspects of the same phenomenon.
