What Causes Electromagnetic Induction?

This is a fundamental topic in Physics that has very deep applications. This article illustrates the principle behind electromagnetic induction and what causes electromagnetic induction.

What is electromagnetic induction?

We will understand the concept of electromagnetic induction with the help of the experiment illustrated below:

Let’s take a coil of copper wire (you can also think of it as a solenoid). Now, at both ends of the coil, between the ends, we connect the galvanometer. Initially, the needle of the galvanometer will be straight because there is no current flowing from it.

Now, we take a magnet. It has two poles, one is the north pole, and the other one is the south pole. When the magnet is at rest, the needle of the galvanometer will remain straight. If we move this magnet, we can see that the needle will start deflecting.

It means that when the magnet moves, then electric current flows into the coil. The direction of the current can be reversed by changing the direction of motion of the magnet or by changing its polarity.

This is because the magnet has magnetic field lines. These field lines are also crossing on the coil. When a magnetic field changes with time through a coil, the current flows in that loop.

This mechanism of magnetic field and magnetic flux producing emf is termed as electromagnetic induction (EMI).

Faraday’s Laws of electromagnetic induction

Faraday’s First Law of electromagnetic induction: Whenever there is a change in magnetic flux linked with a conductor, an electromotive force (EMF) is induced in the conductor. If a conductor forms a closed conducting coil, an induced electric current flows through it. In other words, whenever there is a relative motion between a coil and magnet, an EMF is generated in the conducting coil. If it is a closed electric circuit, an induced electric current flows through it. And the induced EMF lasts as long as the change in flux occurs.

Faraday’s Second Law of electromagnetic induction: The magnitude of the induced EMF is directly proportional to the rate of change/variation in magnetic flux.

Important terms

Galvanometer: It is an instrument or device that can be connected to an electric circuit to determine the current flow from the electric circuit. If the current flows from that electric circuit, the needle will deflect. Hence, it tells us if the current is flowing through the circuit or not. Besides that, it also tells us if an electric current is flowing and in which direction it flows.

Magnetic flux: It is the number of magnetic field lines passing perpendicular through a surface.

Induced current: An electric current produced in a closed circuit by a changing magnetic field is called induced current.

Why does electromagnetic induction take place?

A magnetic field means a voltage liberates a charge to accelerate and move. This does not affect electrons bound by forces holding them firmly in an equilibrium of forces. However, it does have a profound effect on any second electron liberated and accelerated/moved by a second voltage. Two electrons set free and in motion respond to both the voltages.

This dual effect is complex to understand. That is why Maxwell studied each situation separately, defining a fictional magnetic field and then separately calculating the effect on a second moving electron.

When a wire is moved near a magnet or a magnet is moved near a wire, an electric current flows through the wire, which is referred to as electromagnetic induction.

This was illustrated by performing an experiment activity that uses a dummy train transformer, along with the wires connected to the track.

The wires that have been placed next to each other start moving towards each other slowly when the transformer is switched on, and when the transformer is switched off, they start moving to the same position they were placed originally.

This illustrates that moving electrons exert forces on the other moving electrons, as when a transformer is turned on and the wires form a complete closed circuit, an electric current flows through the wires.

This electric current is the stream of electrons flowing steadily through the wires in the electric circuit. So, the two wires that have been placed next to each other depict that the stream of electrons flowing in the wire exerts forces on the other flowing electrons in the other wire.

Electromagnetic induction involves wires and magnets that move in a corresponding direction to each other. The fundamentals of electromagnetic conduction are crucial to our understanding because all the electricity we consume today (except for that produced by solar panels and batteries) comes from the use of the basic principle of electromagnetic induction.

Conclusion

This article discussed the experiment to understand the fundamentals of electromagnetic induction and the other concepts related to electromagnetic induction. This article also explains why the phenomenon of electromagnetic induction takes place. It also explains the various terms associated with the discussion on “why does electromagnetic induction take place?” such as galvanometer, induced current, EMF, etc. which is fundamental to our knowledge on this topic.