Magnetism and Electricity Vocabulary

Vocabulary flashcards covering key terms, definitions, and equations from the magnetism, electricity, and electromagnetism lecture notes.

Magnet

A material or object that produces a magnetic field and possesses a north (N) pole and a south (S) pole.

Magnetic Materials

Materials that are attracted to magnets, which include iron, steel, cobalt, and nickel.

Non-magnetic Materials

Materials that are not attracted to magnets, such as glass and plastic.

Temporary Magnets

Magnetised materials (such as soft iron) that retain their magnetic properties only while inside an external magnetic field and lose them when the field is removed.

Permanent Magnets

Magnetised materials (such as steel) that retain their magnetism after magnetisation because they generate their own continuous magnetic field.

Magnetic Field

A region around a magnet or current-carrying conductor where a magnetic pole experiences a magnetic force.

Conductors

Materials, such as metals and molten ionic substances, that allow electric charge to flow through them due to the presence of free-moving charged particles.

Insulators

Materials, such as rubber, plastic, glass, and wood, that impede the flow of electric charge because they lack free-moving charged particles.

Electric Field

A region in space where an electric charge experiences an attractive or repulsive electrostatic force.

Gold-leaf Electroscope (GLE)

An instrument used to detect electrostatic charge and differentiate between electrical conductors and insulators.

Electric Current

The rate of flow of electric charge passing a given point in a circuit per unit time, expressed as $I = \frac{Q}{t}$ and measured in amperes ($A$).

Conventional Current

The defined direction of electric current flow from a positive terminal to a negative terminal.

Direct Current (d.c.)

An electric current in which electrons flow continuously in one single direction from the negative terminal to the positive terminal.

Alternating Current (a.c.)

An electric current in which the direction of electron flow reverses at regular intervals.

Electromotive Force (e.m.f.)

The electrical work done by a power source in moving a unit charge around a complete circuit, calculated as $\text{e.m.f.} = \frac{W}{Q}$ and measured in volts ($V$).

Potential Difference (p.d.)

The work done by a unit charge passing through a specific circuit component, calculated as $V = \frac{W}{Q}$ and measured in volts ($V$).

Electrical Resistance

A measure of a component's opposition to the flow of electric current, defined by the ratio $R = \frac{V}{I}$ and measured in ohms ($\Omega$).

Kilowatt-hour (kWh)

A unit of electrical energy representing the total energy converted by a $1\,\text{kW}$ appliance operating for a duration of $1\,\text{hour}$.

NTC Thermistor

A temperature-sensitive resistor whose electrical resistance decreases as temperature increases.

Light-Dependent Resistor (LDR)

A light-sensitive resistor whose electrical resistance decreases as light intensity increases.

Diode

A component that allows current to flow through it in only one direction due to extremely high resistance in the reverse direction.

Relay

An electromagnetically operated switch that uses a small current in one circuit to switch on or off a separate circuit carrying a much larger current.

Live Wire

The line wire in a mains supply circuit that delivers alternating electric current from the power grid.

Neutral Wire

The terminal wire in a mains supply circuit that completes the circuit by carrying current back to the power source.

Earth Wire

A low-resistance safety wire connected to metal appliance casings that channels excess current safely into the ground during a short circuit.

Electromagnetic Induction

The process of generating an electromotive force (e.m.f.) across a conductor by moving it through a magnetic field or varying the magnetic field through a coil.

A.C. Generator

A device that converts mechanical energy into an alternating electric current by rotating a coil of wire within a magnetic field using slip rings and carbon brushes.

Transformer

A device consisting of primary and secondary coils wrapped around a soft iron core, used to change the magnitude of an alternating voltage.