Electricity and Magnetism Defenitions revision for test

Year 9 TERM 2

Voltage (V)

The 'push' that drives current in a circuit. Measured in volts (V).

Current (I)

The rate of flow of electric charge. Measured in amperes (A).

Resistance (R)

Opposition to current flow, converting electrical energy to heat. Measured in ohms (Ω).

Ohm’s Law (V = IR)

Relates voltage, current, and resistance: V = IR. Calculate any value if you know the other two.

Ammeter

Measures electric current (in amperes). Connected in series.

Voltmeter

Measures voltage (in volts) across a component. Connected in parallel.

Potential Difference (Voltage)

The difference in electrical potential energy between two points, driving current flow.

Resistance

How much a component impedes current flow. High resistance means difficult current passage.

Electric Circuit

A closed loop allowing continuous electric current flow from a voltage source through components.

Contact Forces

Forces requiring direct physical contact between objects (e.g., pushing, friction).

Non-Contact Forces

Forces acting between objects without contact (e.g., gravity, electric forces).

Gravitational Force

Attractive force between any two objects with mass. Stronger with more massive objects.

Non-Contact Force Field

A region where a non-contact force is experienced (e.g., gravitational, electric, magnetic).

Magnetic Force

Force exerted by a magnetic field on moving charges or magnetic materials.

Electrostatic Force

Attraction or repulsion between electric charges. Like charges repel, opposites attract.

When Magnets Attract

Opposite poles (north and south) attract. Magnetic field lines connect from north to south.

Properties of a Magnetic Field

Strength and direction, strongest at poles. Visualized using magnetic field lines.

Permanent vs. Induced Magnets

Permanent magnets create their own field; induced magnets become magnetic in an external field.

Electromagnet

Magnet with a field produced by electric current in a wire coil. Field disappears when current stops.

Permanent Magnet

Object that creates its own persistent magnetic field without external current.

Generator

Converts mechanical energy to electrical energy using electromagnetic induction.

Lorentz Force

Force on a point charge moving through an electromagnetic field (electric and magnetic).

Motor

Converts electrical energy to mechanical energy using magnetic fields from electric currents.

Solenoid

Coil of wire carrying current, producing a uniform magnetic field inside. Used in electromagnets.

Ohm's Law: Voltage Formula

V = IR. V = Voltage, I = Current, R = Resistance. Calculates voltage.

Ohm's Law: Current Formula

I = V/R. I = Current, V = Voltage, R = Resistance. Calculates current.

Ohm's Law: Resistance Formula

R = V/I. R = Resistance, V = Voltage, I = Current. Calculates resistance.

Electrical Load

Component that consumes electrical energy and performs a function (e.g., light bulb).

Amplifier

Device that increases signal power. Used to boost weak signals.

Insulator

Material resisting current flow due to high resistance (e.g., rubber, plastic).

Conductor

Material allowing easy current flow due to low resistance (e.g., copper, aluminum).

Field Line

Visual representation of force field direction and strength. Shows path of positive charge.

Transistor

Semiconductor device amplifying/switching electronic signals. Key in modern electronics.

Magnetic Field

Region around a magnet/current-carrying wire exerting force on moving charges/magnetic materials.

Series Circuit

Components connected along one path; same current flows through all. Total resistance is the sum.

Parallel Circuit

Components connected across multiple paths; same voltage across all. Total resistance is lower.

Properties of a parallel circuit?

Current is shared among the components; voltage is split.

Properties of a series circuit?

Current is constant among components; voltage stays the same.

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