U3T2:MG:Electromagnetic Induction

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Questions and Answers

Define the term magnetic flux density (B)

The strength of a magnetic field or the number of magnetic field lines per unit area. Measured in weber, Wb.

Define the term magnetic field

Magnetic fields are regions of space where a magnetic force is experienced.

Define the term electromagnetic induction

The production of an EMF or voltage across an electrical conductor due to its dynamic interaction with a magnetic field.

Define the electromotive force (EMF)

A difference in potential that tends to give rise to an electric current; measured in volts V. EMF equals the rate of change of a magnetic flux. Signup and view all the answers

Define Lenz's law

Lenz's law states that the direction of an electric current induced in a conductor by a changing magnetic field is such that the magnetic field created by the induced current opposes changed in the magnetic field that produced it. Lenz's law obeys the law of conservation of energy. This means that the induced EMF causes an induced current that will have a magnetic field (flux), which will oppose the original change in the magnetic field (flux). Signup and view all the answers

Define the term Faraday's Law

Faraday's law explores the relationship between different factors and the magnitude of the induced EMF, while Lenz's law explains how an induced EMF causes an induced current. Faraday's law of induction says that when a magnetic field changes, it causes a voltage, a difference in the electric potential that can make electric currents flow. Signup and view all the answers

Describe the process of inducing an EMF across a moving conductor in a magnetic field

There needs to be a dynamic interaction between a magnetic field (i.e. magnet) and an electrical conductor (i.e. solenoid). As the north pole of the magnet approaches the solenoid, the coil will produce a north pole at this end to repel the incoming magnetic. Work has the be done to overcome the repulsion and cause the magnet to continue to move. The mechanical energy required to do this work is transformed into electrical energy to conserve the overall energy in the system, and obey the law of conservation of energy. A current is induced which will opposed the change in the circuit (Lenz's law). This movement causes an EMF to be produced. Signup and view all the answers

Explain how transformers work in terms of Faraday's law and electromagnetic induction

Transformers are devices that transfer an alternating current from one circuit to another. Transformers operate on the principle of Faraday's law by which the varying magnetic field (flux) in one coil induces an EMF is the second coil it is connected to. 1) Magnetic field in coil 1 will induce a current in coil 2. 2) The polarity of this magnetic field will constantly change due to AC (alternating current). 3) This causes the electrons in the second coil to be disturbed and causes them to move. Signup and view all the answers

Study Notes

Magnetic Flux Density (B)

The strength of a magnetic field at a particular point.
Measured in Tesla (T).
The force exerted on a moving charge in a magnetic field is proportional to the magnetic flux density.

Magnetic Field

A region of space where a magnetic force can be experienced/detected.
Created by moving electric charges, such as currents in wires or the spin of electrons.
Characterized by magnetic field lines, which represent the direction of the force on a north magnetic pole.

Electromagnetic Induction

The phenomenon of producing an electromotive force (EMF) in a conductor by changing the magnetic flux through it.
It is the basis for electric generators and transformers.

Electromotive Force (EMF)

The energy per unit charge provided by a source of electrical energy to move charges around a circuit.
Not a force, but a potential difference.
Measured in volts (V).
Induced EMF can be created by changing magnetic flux through a coil.

Lenz's Law

The direction of the induced electromotive force (EMF) in a circuit is such that it opposes the change that produced it.
This law is based on the principle of conservation of energy.

Faraday's Law

The magnitude of the induced EMF is proportional to the rate of change of magnetic flux through a circuit.
Formally: EMF = -N(dΦ/dt), where N is the number of turns in a coil, and dΦ/dt is the rate of change of magnetic flux.

Inducing EMF Across a Moving Conductor in a Magnetic Field

When a conductor moves through a magnetic field, the free electrons in the conductor experience a magnetic force, causing them to move.
This movement of electrons creates an electrical current and thus an EMF.
The magnitude of the induced EMF is proportional to the speed of the conductor, the strength of the magnetic field and the length of the conductor.

Transformers and Faraday's Law

Transformers use Faraday's Law to change the voltage of an alternating current (AC).
A primary coil with N1 turns is connected to an AC source.
An alternating current in the primary coil creates a changing magnetic flux.
This changing magnetic flux links to a secondary coil with N2 turns.
The changing magnetic flux induces an EMF in the secondary coil, proportional to the rate of change of magnetic flux and the number of turns in the secondary coil.
The voltage ratio between the primary and secondary coils is proportional to the ratio of the number of turns in each coil: V2/V1 = N2/N1

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Description

Test your understanding of the concept of magnetic flux density (B) with this quiz. Explore its definition, importance, and applications in physics. Perfect for students and enthusiasts looking to deepen their knowledge in electromagnetism.