NCEA L1 Science key terms

The rate at which electric charge flows past a point in a circuit, measured in amperes. One ampere means one coulomb of charge passes each second.

A fundamental property of matter that causes it to experience forces in electric fields. Electrons carry negative charge and protons carry positive charge; the unit is the coulomb.

The energy transferred per unit charge between two points in a circuit, measured in volts. It is often described as the electrical push that drives current.

A measure of how strongly a component opposes the flow of electric current, measured in ohms. Higher resistance means less current for the same applied voltage.

The relationship stating that for a metallic conductor at constant temperature, voltage equals current multiplied by resistance (V = IR). It lets you calculate any one of the three if the other two are known.

A circuit in which components are connected one after another so there is only one path for current. The current is the same everywhere, and the supply voltage is shared between components.

A circuit in which components are connected across the same two points, giving each its own branch. The voltage across each branch is the same and the total current splits between them.

A source of electrical energy that converts stored chemical energy into electrical energy, providing a voltage that drives current around a circuit.

A material that allows electric charge to flow through it easily because it contains loosely held electrons, such as copper or aluminium. Metals are the most common examples.

A material that does not allow electric charge to flow through it easily, such as plastic, rubber or glass. Insulators are used to coat wires and keep people safe.

The rate at which electrical energy is converted into other forms, measured in watts. In a circuit it equals voltage multiplied by current (P = VI).

The capacity to do work or cause change, measured in joules. In electricity it is transferred from a source to components, where it may become light, heat, sound or motion.

The proportion of input energy that is converted into useful output energy, often expressed as a percentage. The rest is usually lost as heat or sound.

A magnet produced by passing electric current through a coil of wire, often wrapped around an iron core. Its magnetism can be switched on and off and its strength varied.

The region around a magnet or current-carrying wire where a magnetic force can be detected. It is represented by field lines showing direction and strength.

One of the two ends of a magnet, called north and south, where the magnetic effect is strongest. Like poles repel each other and unlike poles attract.

A coil of wire wound into a cylinder shape that produces a magnetic field when current flows through it. Placing an iron core inside makes a stronger electromagnet.

A device that converts kinetic energy into electrical energy by moving a coil of wire through a magnetic field, or by moving a magnet near a coil.

The process in which a changing magnetic field through a coil induces a voltage in that coil. It is the principle behind generators and transformers.

A device with two coils sharing a magnetic core that changes the voltage of an alternating current supply. It can step voltage up or down but does not change the total power.

A safety component containing a thin wire that melts and breaks the circuit if the current becomes too high, protecting wiring and people from overheating or fire.

A reusable safety switch that automatically opens a circuit when current exceeds a safe level, then can be reset once the fault is fixed.

A component whose resistance can be adjusted to control the current or voltage in a circuit. It is used in dimmer switches and volume controls.

An instrument used to measure the voltage across a component. It is connected in parallel with the component so it measures the difference in energy per charge.

An instrument used to measure electric current in a circuit, connected in series so the current flows through it. It is measured in amperes.

A negatively charged subatomic particle found outside the nucleus of an atom. The movement of electrons through a conductor is what we call electric current.

A testable prediction about what will happen in an investigation, based on prior knowledge or observation. It must be something you can measure and check with evidence.

Any factor in an investigation that can change. Scientists identify which variables to change, measure or keep the same so the results are meaningful.

An investigation in which only the independent variable is changed while all other relevant conditions are kept the same, so any effect on the outcome can be attributed to that change.

The consistency of results when a measurement or investigation is repeated. Reliable results are close to each other and improve confidence in the conclusion.

How close a measured value is to the true value. Accuracy differs from reliability, which is about consistency between repeated measurements.

The general pattern shown by data, such as values increasing, decreasing or levelling off as the independent variable changes. Trends are described in a conclusion.

Energy from sources that are naturally replenished on a human timescale, such as sunlight, wind, moving water and geothermal heat. These sources produce little or no greenhouse gas while operating.

Energy from sources that exist in limited amounts and cannot be replaced quickly, such as coal, oil, natural gas and uranium. Burning fossil fuels releases carbon dioxide.

The principle that energy cannot be created or destroyed, only transferred or transformed from one form to another. The total energy in a closed system stays constant.

A standard drawing that uses recognised symbols to show how components in an electrical circuit are connected, without showing their physical appearance.

An accidental low-resistance path that lets a large current bypass the intended components. It can overheat wires and is why fuses and circuit breakers are used.