Magnetism and Electromagnetism

Vocabulary-style practice flashcards covering fundamental concepts of magnetism, electromagnetism, and their applications as outlined in the AQA GCSE Physics Topic 7 notes.

Permanent Magnets

Magnets that are always magnetic and always have poles.

Induced Magnets

Materials like Iron, Nickel, and Cobalt that do not have fixed poles but can be made into temporary magnets by 'stroking' them with a permanent magnet to align their domains.

Magnetic Field Lines

Lines used to represent a magnetic field that always point away from the North pole and toward the South pole.

Plotting Compasses

Small compasses which show the direction of the magnetic field at a certain point.

Right hand grip rule

A rule used to dictate the direction of the magnetic field produced by a current flowing through a wire.

Solenoid

A coil of wire where the magnetic field shape is similar to a bar magnet; coiling the wire enhances the magnetic effect by aligning the field into a single giant field.

Soft iron core

A core placed in the center of a solenoid to increase its strength because magnetic field lines pass through it more easily than through air.

The Motor Effect

The phenomenon where a current-carrying wire and a magnet exert a force on each other because their two magnetic fields interact.

Fleming’s Left Hand Rule

A rule where each direction (Force, Magnetic Field, and Current) is at $90^\text{∘}$ to each other, used to work out an unknown factor.

Magnetic Flux Density

The number of flux lines per metre squared, measured in $Tesla$.

$$F = BIl$$

The equation for calculating force where $F$ is Force, $B$ is magnetic flux density, $I$ is current, and $l$ is length.

Electromagnetic Induction

The process where a potential difference is induced across a conductor when there is relative movement between the conductor and a magnetic field, or when the magnetic field changes.

Alternator

A basic electric generator that produces an alternating current (AC) as the coil of wire rotates and cuts through a magnetic field.

Split ring commutator

A device used in a dynamo to reverse the current each half-rotation so the current remains positive, producing direct current (DC).

Dynamo

A system or electric generator that produces direct current (DC) using a split ring commutator.

Step up transformer

A transformer with more coils on the secondary than the primary, which increases the voltage as the changing field cuts through more secondary wire.

Step down transformer

A transformer with fewer coils on the secondary than the primary, resulting in a smaller potential difference forming on the secondary.

Dynamic Microphones

Devices that use pressure variations in sound waves to move a coil of wire within a magnetic field, inducing a current proportional to the sound signal.

Loudspeakers

Devices where current flows into a coil to interact with a magnetic field, causing a cone to move and produce sound via pressure variations.