# Magnetism: Electromagnetic Induction

## Magnetism: Electromagnetic Induction

• Electromagnetic Induction is the process where an electric current or voltage is produced by a change in magnetic field. Michael Faraday discovered this principle in 1831.
• A magnetic field is created around a wire when an electric current is passed through it. This is the principle of electromagnetism.
• Changing the magnetic field in a coil of wire can induce a voltage. This by itself may not cause a current but if the circuit is closed, a current will flow.
• The induced voltage can also be increased by increasing the rate of change of the magnetic field. This can be achieved either by moving the magnet more quickly or changing the direction of the magnetic field more rapidly.
• Faraday’s Law states that the induced electromotive force (emf) in a closed circuit is proportional to the rate of change of magnetic flux through the circuit. This is one of the fundamental principles underlying electromagnetic induction.
• The direction of the induced current or induced emf can be determined by Lenz’s Law. According to Lenz’s Law, the induced emf and the change in flux have opposite signs. This means the induced electromagnetic field acts against the change that produced it.
• Electrical generators and transformers work based on the principle of electromagnetic induction.
• In electric generators, mechanical energy is converted into electrical energy. This happens by rotating a coil within a magnetic field or moving a magnet within a stationary coil.
• Alternating current (AC) is generated when a coil is spun in a magnetic field. The direction of the current changes with each half revolution, creating a wave-like pattern.
• Transformers utilise electromagnetic induction to increase or decrease voltages in alternating current circuits. They are made up of two coils called the primary coil and the secondary coil.
• In transformers, a change in current in the primary coil induces a voltage in the secondary coil, allowing us to transform voltage levels with little energy loss. If the secondary coil has more turns than the primary, the outgoing voltage is increased (step-up) and the other way around (step-down).
• Electromagnetic induction is widely used in technology and everyday life, including power generation, in transformers, induction stoves, electric vehicles, and credit card readers.