Did you know that electrons act like tiny little magnets? Because each electron has a magnetic dipole moment. You don’t need to understand what is a magnetic dipole moment. The only important fact here is electrons act like tiny magnets, therefore as poles repel, opposites attract.
Faraday’s law of induction is a basic principle of electromagnetism that explains how an electric current can be generated by a changing magnetic field.
The key idea behind Faraday’s law is that a changing magnetic field produces an electric field. This means that if you move a magnet around, it will create an electric current in any nearby conductor (such as a coil of wire). Similarly, if you change the strength or direction of a magnetic field, this will also induce an electric current in nearby conductors.
How to Make Electricity With Magnets?
Electricity can be generated using magnets and coils of wire. By moving a magnet around a coil of wire, or by moving a coil of wire around a magnet, electrons within the wire are pushed and we can make an electrical current. This process is called electromotive force (EMF).
However, it doesn’t have to be a wire. Any good conductor would work as well. This is the principle that practical electrical generators are based on.
STEP 1: Take a good conductor and a magnet.
STEP 2: Next, move the magnet around the conductor.
STEP 3: This will cause electrons (the charge) to flow and create an electric current.
EMF – Electromotive Force
The EMF, or electromotive force, is the force that drives electrons in a circuit. More generally, it is the measure of energy given to each coulomb of charge by a power source.
However, technically speaking, EMF is not itself a force or energy; rather, it is the potential to provide energy. The term “force” can be somewhat misleading here – what we’re talking about is the potential for providing energy within a system.
But, why can’t we just call EMF the potential difference? Both EMF and terminal potential difference (V) are measured in volts, but they are not quite the same thing. The potential difference is the amount of energy used by the one coulomb of charge while the EMF is the measure of energy that it gives to each coulomb of charge. EMF is equal to the terminal potential difference under one condition. If there is no current flow, EMF is equal to the terminal potential difference.
EMF can be misleading sometimes. Sometimes people read EMF as Electromagnetic Force and it’s completely a different concept. The electromagnetic force is a type of interaction that happens between electrically charged particles.
Another misleading factor is the word “force”. Electromotive Force – EMF is not an actual force or energy.
Faraday’s First Law
Faraday’s First Law states that whenever a conductor is placed in a varying magnetic field an EMF gets induced across the conductor. This means that if the magnetic field around a conductor is changing, an electromotive force will be induced in the conductor. This EMF can cause current to flow through the conductor if it forms a complete circuit.
You can vary the magnetic field by moving either the magnet or coil relative to each other, or by rotating the coil relative to the direction of the magnetic field.
Faraday’s First Law of Induction Key Concepts
- Faraday’s Law of Induction states that when a conductor is moved through a magnetic field, an electric current will be induced in the conductor. This current will flow in the direction that opposes the motion of the conductor through the magnetic field.
- The phenomenon described in Faraday’s Law only occurs when there is relative motion between a magnet and a conductor. If either the magnet or the conductor is stationary, no inducement takes place.
- The effect observed also requires that both objects are close to each other – if they are too far apart, then again no induction happens.
- The size of the induced current is proportional to the rate at which the conductor is moved through the magnetic field.
- The direction of the induced current can be determined using what is known as Fleming’s left-hand rule.
- In Faraday’s Law of Induction, the observable phenomenon only depends on the relative motion between a conductor and magnet, not the absolute motion.
Lenz’s Law
Lenz’s Law is based on the principle of conservation of energy, which means that energy cannot be created or destroyed. The law ensures that there is always some form of resistance to changes in electric currents, preventing free energy from being produced. When an emf is generated by a change in magnetic flux according to Faraday’s Law, the polarity of the induced emf produces a current whose magnetic field opposes the change which produces it. This keeps the overall magnetic flux constant.
Further, Lenz’s Law is part of the bigger picture of Maxwell’s equations, which are a set of equations that describe all known electric and magnetic phenomena. These equations show that electricity and magnetism are two manifestations of the same thing – electromagnetism. Which one you observe depends on your reference plane.
Faraday’s Second Law of Electromagnetic Induction
Relationship Between EMF And The Rate of Change of Magnetic Flux
Faraday’s second law of induction states that the EMF induced in a circuit is proportional to the rate of change of magnetic flux. The formula for this relationship is:
| ∅ | Change in flux |
| N | Number of turns |
| t | Time taken |
| (∆∅)/Δt | Rate of change of magnetic flux |
Further, the induced EMF will be maximum when the rate of change of magnetic flux is maximized. For example, if the coil is moved quickly through a magnetic field, more flux will be cut and the induced EMF will be greater.
For example, if you have a coil of wire moving through a magnetic field, the changing flux will induce an EMF in the coil. The faster the coil moves, or the stronger the magnetic field, the larger the induced EMF will be.
Transformers And Faraday’s Law of Induction
Faraday’s law of induction is the principle that underlies how transformers work. A transformer typically consists of two coils, a primary coil, and a secondary coil. The number of turns in each coil is different. When an alternating current flows through the primary coil, it generates a magnetic field around it. This changing (or time-varying) magnetic flux then induces a voltage across the secondary coil according to Faraday’s law.
Even if I said that the number of coils in the primary and the secondary is different the transformer would still work. But it would be useless because the input voltage and current would be the same as the output voltage and current under the ideal conditions. The secondary coil’s purpose is to have more or fewer turns than the primary so that it can step-up or step-down the voltages.
The transformer is an essential part of our electrical grid, step down transformers are used at generating stations to increase voltage before transmission over long distances, while distribution substations contain step-up transformers that decrease voltage for safe domestic use.
The ratio of the number of turns in the primary coil to the number of turns in the secondary coil determines whether the transformer increases or decreases voltage.
If the number of turns in the secondary coil is greater than the number of turns in the primary coil, then the transformer acts as a “step-up” transformer and increases the voltage. If the number of turns in the secondary coil is less than the number of turns in the primary coil, then the transformer acts as a “step-down” transformer and decreases voltage.
Common Applications of Faraday’s Law of Induction
Wireless Charging
The technology of wireless charging is based on Faraday’s Law of Induction. Wireless charging pads use a magnetic field to inductively transfer energy between the pad and the device being charged. The key component of this technology is the induction coil, which creates a varying electromagnetic field when an alternating current flows through it. When this coil is placed near another conductive object (such as a phone), currents are induced in that object by electromagnetic induction; these induced currents can then be used to power the phone wirelessly.
Magnetic Levitation Trains
Magnetic levitation trains, also called maglev trains, rely on Faraday’s Law of Induction for their operation. These trains float above their track thanks to powerful magnets mounted underneath them. It moves forward by using magnets to create a magnetic field that interacts with the track, propelling the train forward. To stop the train, the magnets are turned off and brakes are applied. But there is only a handful of successful maglev trains in the world.
Induction Furnaces
Induction furnaces are used for melting metals and alloys; they work by inducing currents in a conductive material placed inside them. The furnace contains an induction coil that carries alternating current; when this coil is placed near a conducting object, eddy currents are induced in that object by Faraday’s Law of Electromagnetic Induction. These eddy currents create heat, which heats the metal or alloy.
Electric Guitar Pickups
Electric guitar pickups work by using the principle of electromagnetic induction. When a string is plucked on an electric guitar, it creates a magnetic field around itself. This moving magnetic field then induces a current in the coil of the pickup, which is then amplified and sent to an amplifier.
Magnetic Braking
Magnetic braking refers to the process whereby an electrical conductor is slowed down by the magnetic field of a permanent magnet or electromagnet. This happens because as the conductor moves through the magnetic field, eddy currents are generated in it. These eddy currents dissipate some of the kinetic energy of the conductor into heat, and this results in a slowing down of its motion.
Current Clamps
The current clamp is a device used to measure electric currents. The clamp-meter contains two large coils, which are placed around the conductor that is to be measured. When the meter is closed, the circuit is completed and a current is induced in the coils. This current can then be measured and displayed on the meter’s display.
Generators
A generator is a device that converts mechanical energy into electrical energy. The principle of operation for a generator is also based on Faraday’s law of induction. When a conductor is moved through a magnetic field, an electromotive force (EMF) is induced in the conductor. This EMF can then be used to drive an electric current through a load.
Induction Motors
An induction motor is a type of electric motor that uses electromagnetic induction to create mechanical rotation. Electromagnetic induction occurs when an electrical conductor is exposed to a changing magnetic field. This induces an electric current in the conductor, which in turn creates its magnetic field. The interaction between these two fields causes the rotor (the moving part of the motor) to rotate, effectively turning the shaft and powering the device attached to it.
Kitchen Hobs
In Kitchen Hobs, Faraday’s Law of Induction is used to heat an iron core through a coil of wire. The current passing through the coil creates a magnetic field, which inducts (or heats) the iron core. This principle is called electromagnetic induction heating, and it is how most induction hobs work.
Transformers
Transformers, as we discussed earlier, work due to Faraday’s law of induction. In order for a transformer to work, there must be two windings (or coils) of wire. The first winding is called the primary winding and the second is called the secondary winding. The transformer is a device that uses Faraday’s law of induction to convert AC voltage from one level to another. It consists of two windings, the primary and the secondary. When AC passes through the primary winding, it creates a varying magnetic flux. This field then induces an AC voltage in the secondary winding via electromagnetic induction.
Conclusion
Faraday’s law of induction is a basic principle of electromagnetism that explains how a changing magnetic field can generate an electric current in a conductor. The induced EMF will be maximum when the rate of change of magnetic flux is maximized, which means that if the magnetic field around a conductor is changing rapidly, it will induce a large EMF in the conductor.
It’s one of the most important laws in electromagnetism. It explains how a changing magnetic field can induce an electric current in a nearby conductor. This principle forms the basis for many devices, including transformers, generators, and inductors.
About Post Author
