Magnetic Induction And Faraday's Law - SS3 Physics Lesson Note

Magnetic induction is the process by which a changing magnetic field induces an electric field and an electric current in a conductor. This phenomenon is known as Faraday's law of induction, named after the physicist Michael Faraday, who first described it in the early 19th century.

Faraday's law states that when the magnetic field through a loop of wire changes, an electromotive force (EMF) is induced in the wire, causing a current to flow. The magnitude of the induced EMF is proportional to the rate of change of the magnetic field and the number of turns in the loop. This relationship is described by the equation:

EMF = -dΦ/dt

 

where EMF is the induced electromotive force, Φ is the magnetic flux through the loop, and dt is the change in time.

Magnetic induction has many practical applications. One of the most common is the generation of electrical power. Electric generators use Faraday's law to convert mechanical energy into electrical energy. The generator has a coil of wire that rotates inside a magnetic field, causing the magnetic flux through the coil to change and inducing an EMF in the wire. This EMF causes a current to flow in the wire, which can be used to power electrical devices.

Magnetic induction is also used in transformers, which are devices that transfer electrical energy from one circuit to another. Transformers consist of two coils of wire wrapped around a common iron core. An alternating current in the primary coil generates a changing magnetic field, which induces an alternating current in the secondary coil. The voltage and current in the secondary coil are proportional to the ratio of the number of turns in the primary and secondary coils.

In summary, magnetic induction is the process by which a changing magnetic field induces an electric field and an electric current in a conductor. This phenomenon is described by Faraday's law of induction and has many practical applications in the generation and transmission of electrical power, as well as in transformers and other electrical devices.