Electromagnetic Induction and Faraday's Law - SS2 Physics Lesson Note

Electromagnetic induction is a fundamental concept in physics that describes the generation of an electromotive force (EMF) or voltage in a conductor when it is exposed to a changing magnetic field. This phenomenon was discovered by Michael Faraday in the 19th century and is known as Faraday's law of electromagnetic induction.

Faraday's Law of Electromagnetic Induction:

Faraday's law states that the EMF induced in a closed loop of wire is directly proportional to the rate of change of magnetic flux passing through the loop. The magnetic flux (Φ) is the product of the magnetic field strength (B) and the area (A) perpendicular to the magnetic field: Φ = B x A. Mathematically, Faraday's law is expressed as: EMF = -dΦ/dt, where EMF is the induced electromotive force and dΦ/dt represents the rate of change of magnetic flux.

Induced EMF and Lenz's Law:

According to Faraday's law, a changing magnetic field induces an EMF in a conductor. This EMF can drive an electric current if a complete circuit is formed. Lenz's law, a consequence of Faraday's law, states that the direction of the induced current opposes the change that produced it. It ensures the conservation of energy. Lenz's law can be understood through the right-hand rule: if the magnetic field increases, the induced current creates a magnetic field opposing the increase. If the magnetic field decreases, the induced current creates a magnetic field opposing the decrease.

Factors Affecting Induced EMF:

-       The magnitude of the induced EMF depends on the rate of change of magnetic flux, the number of turns in the coil, and the properties of the conductor.

-       Increasing the rate of change of magnetic field or the number of turns in the coil leads to a higher induced EMF.

-       The magnetic field strength and the area of the loop also affect the magnitude of the induced EMF.

Applications of Electromagnetic Induction:

-       Electromagnetic induction has various practical applications in everyday life and technology.

-       Electric generators use the principle of electromagnetic induction to convert mechanical energy into electrical energy.

-       Transformers utilise electromagnetic induction to transfer electrical energy between different voltage levels efficiently.

-       Induction cooktops use alternating magnetic fields to generate heat in the cookware.

-       Magnetic card readers, induction motors, and wireless charging systems also rely on electromagnetic induction.

Electromagnetic induction is a crucial concept in the field of electricity and magnetism. It explains how changing magnetic fields can produce electric currents and how energy can be transferred between different forms. Faraday's law of electromagnetic induction laid the foundation for the development of many important technologies, and its applications continue to shape our modern world.