Physics - Magnetism

What is induced magnetism?

Induced magnetism is when a magnet grants magnetic properties to a nearby material without direct contact, typically achieved when the material is within a magnetic field.

What is a magnetic field

A region around a magnet where magnetic forces can be detected, influencing magnetic materials and charged particles.

What is the effect on current in a magnetic field?

The effect on current in a magnetic field is known as electromagnetic induction, where a changing magnetic field can induce an electromotive force (EMF) and generate an electric current in a conductor.

If the current is large

in a magnetic field, it can produce a stronger magnetic field around the conductor, leading to significant electromagnetic effects such as increased force on nearby magnetic materials.

What is magnetic flux density

Magnetic flux density, also known as magnetic field density, is a measure of the strength and direction of a magnetic field at a given point in space, represented by the symbol B, and is measured in teslas (T).

What is the definiton of magnetic flux density

It is a vector whose magnitude is equal to the force that would ne experienced by a conductor of length 1mm carrying a current of 1A at right angles to the field at that point and whose direction is the direction of the force on a north pole placed at that point

What is 1 Tesla?

1 Tesla is defined as the magnetic flux density that produces a force of one newton on a one-meter length of conductor carrying a current of one ampere, oriented perpendicular to the magnetic field.

F = QVB

F = Force

Q = charge (coulombs)

V = Velocity

B = Magnetic flux density (tesla)

How do you find the radius of a path that a moving charged particle is making in a magnetic field?

Use mv²/r = qvb

Combine circular motion formulae and the magnetic field ones.

What happens if there are two conductors with currents in opposite directions?

They will experience a force of attraction.

Definition of the ampere?

The anpere (A) is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible cross section and placed 1 metre apart in a vacuum, would produce a force on each conductor of 2×10^-7 newtons per metre of length

Coulomb definiton

The coulomb (C) is the amount of charge that passes any point in a circuit when a current of 1 ampere flows for 1 second

F = I L B

If a conductor of LENGTH L carrying a current I is placed at a right angle to a magnetic field of flux density B, it will experience force F.

What is electromagnetic induction?

Whenever the magnetic field passing through a coil changes, an emf appears in the coil. This phenomenon is called electromagnetic induction

How to demonstrate electromagnetic induction?

A coil, with both ends connected to a bulb and a magnet.

Move magnet through coil quickly.
An emf will be produced.

What is the unit of magnetic flux?

The weber (Wb)

It is the magnetic flux density over an area of 1m² is 1 Tesla, it is 1 Weber.

Φ = BA

Φ = Weber

B = Magnetic Flux Density

A = Area

What is Faraday’s Law of Electromagnetic Induction?

Fardays law states that the size of the inducted emf is directly proportional to the rate of change of flux.

Induced EMF e formula for faradays law

E = -dΦ/dt

(change in webers)/(time taken)

What is Lenz’s Law

States that the direction of an induced current is always such as to oppose the change producing it.

eg magnet moving toward coil
- induced current will flow opposite direction to the motion of the magnet.

What are some examples of generators? What is an electrical generator?

Electricity power generators
Alternator in a car
Dynamo in a bicycle

An electrical generator converts mechanical energy into electrical energy through electromagnetic induction.

what is the rms value

The root mean square (RMS) value is a statistical measure used to calculate the effective value of an alternating current (AC) or a varying signal. It represents the equivalent direct current (DC) value that delivers the same power to a load.

eg domestic power is supplied at an rms voltage of 230 volts. Find the peak voltage

230 x root2 = 325.5 volts.

What is mutual induction

When a change in current in one coil induces a voltage in another nearby coil.

What is self induction?

Self induction is the process by which a changing current in a coil induces a voltage in itself. This occurs due to the magnetic field created by the current in the coil.

What is the formula for transformers?

The formula for transformers is Vp/Vs = Np/Ns, where Vp and Vs are the primary and secondary voltages, respectively, and Np and Ns are the number of turns in the primary and secondary coils.