Miniature Circuit Breakers (MCBs)

Miniature Circuit Breakers raptopicIdly replaced fuses because they provtopicIde a higher degree of protection. MCB does not melt like typical fuses do when a current flows through them. This is because MCB operates based on the magnetic field produced by electricity. 

When the current in a circuit reaches a certain threshold, these switches will immediately shut off automatically. We switch them ON, and the current flows, completing the circuit once again. You may be curious as to know what is the magnetic influence of electric current on the nearby area, which causes the circuit to break the flow of electricity. Now, we shall study the magnetic impact of electric current.

Magnetic effect of electric current

If an electric current flows through a conductor, the conductor starts creating a magnetic field and acts like a temporary magnet. The physicist Hans Christian Oersted discovered this phenomenon, known as the magnetic effect of electricity. 

Mr. Oersted noticed that when an electric current is transmitted over a wire and a compass is kept at a nearby distance, the needle of the compass deviates from its normal North-South orientation and orients itself based on the strength of the magnetic field.

A magnetic effect is produced by a straight wire carrying an electrical current. Only by using a lengthy coil of wire as opposed to a straight wire is the magnetic effect enhanced. 

If the coil of wire is twisted around a rod of iron and then electricity is passed through it, the magnetic effect is boosted even more.

Electromagnets

An electromagnet is a kind of magnet that is created by passing an electric current through a conductor like iron. Electromagnets operate due to the magnetic effect of electricity and have a temporary magnetic field as long as the current is passed through the conductor. 

Can we make an electromagnet?

Yes, you can make an electromagnet with the use of a coil or even with a wire that is wound around a piece of iron. The iron becomes magnetic only when an electric current is conducted through the coil, and thus, it is termed as an electromagnet or temporary magnet.

When the two ends of the coil are connected to a cell, current flows through the coil, creating a magnetic effect. The iron rod is magnetized by the magnetic effect and the iron rod is transformed into an electromagnet. 

As long as a current flows through the coil of an electromagnet, its magnetism persists. Therefore, if we turn OFF the current in the coil, the iron rod will lose its magnetic effect and cease to function as a magnet.

How can we increase the strength of the magnetic field?

There are two ways to increase the strength of an electromagnet and this can be achieved in the following ways:
⦁    Increasing the coil's current and the size of the coil
⦁    Increasing the coil's number of turns

Electromagnetic Applications

Some of the applications of the electromagnet are as follows:

⦁    Electric bells, electric fans, and electric motors are just a few examples of the many electrical devices that make use of the concept of electromagnets.
⦁    These types of magnets are used in electric generators that need an extremely powerful magnetic field.
⦁    Electromagnets are used to deviate the electron beam of the image tube in a television.
⦁    Electromagnets are often used in the process of magnetically separating iron ores from other natural substances.
⦁    Electromagnets are used to generate powerful permanent magnets.

UpstopicIdes of using electromagnets over permanent magnets

Electromagnets are a transient sort of magnet since their magnetism only lasts as long as current flows through the coil. In many instances, an electromagnet is superior to a permanent magnet. The following are a few of the benefits of electromagnets over permanent magnets:

⦁    An electromagnet's magnetism may be turned on or off at the flip of a switch, depending on what the user prefers, which is not the case with a permanent magnet.
⦁    A powerful electromagnet may be created by increasing the number of turns in the coil and the current going through it. On the other hand, the strength of a permanent magnet can never be increased to such a level.

Electric Bell

A bell is powered by the magnetic effect of a current, containing an electromagnet. Let us also investigate its structure and operation.

Electric Bell Construction

The electromagnet of the bell's electromagnet is U-shaped which forms a magnet. A short iron bar known as the armature is placed in front of the electromagnet's poles. The bottom end of the iron bar is connected to a flat spring, which is in turn fastened to a metal bracket. Attached to the top end of the iron bar is a clapper or striker. A metal gong is positioned below the clapper. The clapper is also called a hammer or striker.

Functioning of Electric Bell

We initially hit the push button switch to ring the bell before we do anything else. The moment you press the switch, electricity flows through the electromagnet's coil, and completes the circuit, magnetizing the iron core along with the coil. At this point, the electromagnet is attracted to the iron armature.

Consequently, when the armature advances towards the electromagnet's poles, the clapper or hammer attached to it hits the gong, producing a ringing sound and this is how a bell rings.

As the armature comes closer to the magnet, the contact that it has with the contact screw will eventually be broken. As a result, the electric circuit is broken and no current passes through the magnetic coil. 

The electromagnet temporarily loses its magnetism, causing the armature to no longer be attracted to it. The flat spring returns the iron armature to its initial position, and the striker or hammer moves away from the gong as well.

As soon as the armature meets the contact screw again, the circuit is completed and electricity begins to flow through the magnetic coil once again. The magnetic once again draws the iron armature, causing the striker to hit the gong and produce a sound.

Therefore, this process of ‘make and break’ in the electric circuit keeps on going as the switch is pressed. This causes the armature to vibrate quickly forwards and backward, causing the striker to hit the gong. Thus, the striker quickly hits the gong to produce an almost continuous sound.

To know more about electromagnetism or to see an animation on the functioning of an electric bell, you can check out our vtopicIdeos.