Physics: Electricity, Circuit Analysis, and Scientific Investigation

Static electricity

A build-up of electric charge on an object that remains at rest rather than flowing continuously.

Electron

A negatively charged subatomic particle loosely held outside the nucleus that moves between materials to transfer electric charge.

Electrical conductor

A material, such as copper or gold, that allows electric charges to flow freely with very low resistance.

Electrical insulator

A material, such as rubber, wood, or plastic, that resists the flow of charges and prevents electric current.

Electric current

The rate of flow of electric charge passing a point in a circuit per second, measured in amperes ($\text{A}$).

Voltage (Potential difference)

The amount of electrical energy possessed by or transferred per unit of electric charge between two points, measured in volts ($\text{V}$).

Electrical resistance

The opposition to the flow of electric charge through a conductor or component, measured in ohms ($\Omega$).

Ohm's Law

The principle stating that current through a conductor is directly proportional to the potential difference across it: $V = I \times R$.

Series circuit

An electrical configuration where all components are connected along a single loop, maintaining an identical current through each component.

Parallel circuit

An electrical configuration containing two or more separate branches, where each branch experiences the same voltage across it.

Ammeter

An instrument connected in series within a circuit path to measure the size of the electric current.

Voltmeter

An instrument connected in parallel across a power source or load to measure potential difference.

Short circuit

A pathway within a circuit that has little or no resistance, causing high current to bypass components and risk overheating.

Ohmic conductor

A device or material with a constant resistance whose voltage-versus-current graph displays a linear relationship.

Non-ohmic conductor

A device, such as a light globe or LED, with variable resistance that produces a curved voltage-versus-current graph.

Independent variable

The condition or factor deliberately changed by the experimenter during an investigation.

Dependent variable

The factor measured or observed to assess the effect of the manipulated condition.

Systematic error

A repeatable error caused by faulty calibration or improper use of equipment that biases measurements consistently high or low.

Random error

An unpredictable experimental variation caused by estimation or fluctuating conditions, minimized by averaging multiple trials.

Static electricity

A build-up of electric charge on an object that remains at rest rather than flowing continuously.

Electron

A negatively charged subatomic particle loosely held outside the nucleus that moves between materials to transfer electric charge.

Proton

A positively charged subatomic particle tightly held within the atomic nucleus that cannot easily move.

Neutron

An uncharged subatomic particle with zero electric charge situated inside the atomic nucleus.

Law of electric charges

The principle stating that like charges repel each other, whereas opposite charges attract each other.

Positively charged object

A body that has transferred away electrons, leaving it with fewer electrons than protons.

Negatively charged object

A body that has gained electrons from another material, leaving it with more electrons than protons.

Electrical conductor

A material, such as copper or gold, that allows electric charges to flow freely with very low resistance.

Electrical insulator

A material, such as rubber, wood, or plastic, that resists the flow of charges and prevents electric current.

Electric current

The rate of flow of electric charge passing a point in a circuit per second, measured in amperes ($\text{A}$).

Conventional current

The established circuit standard that defines charge movement as flowing from the positive terminal toward the negative terminal.

Electron flow

The physical drift of negatively charged particles through wires from the negative terminal toward the positive terminal.

Voltage (Potential difference)

The amount of electrical energy possessed by or transferred per unit of electric charge between two points, measured in volts ($\text{V}$).

Chemical cell

A power source that converts stored chemical potential energy into electrical energy via internal chemical reactions.

Electrical load

A component within a circuit, such as a globe or motor, that opposes charge flow and converts electrical energy into useful forms.

Voltage drop

The loss of electrical potential energy per unit charge as it overcomes opposition while traveling through a component.

Electrical resistance

The opposition to the flow of electric charge through a conductor or component, measured in ohms ($\Omega$).

Resistor colour code

A system of colored bands printed onto resistors to indicate their resistance value and tolerance.

Ohm's Law

The principle stating that current through a conductor is directly proportional to the potential difference across it: $V = I \times R$.

Series circuit

An electrical configuration where all components are connected along a single loop, maintaining an identical current through each component.

Current in a series circuit

Remains constant across all components because electric charge can only follow one single closed loop.

Voltage in a series circuit

Shared across each connected load so that the sum of the individual potential drops equals the power supply potential.

Parallel circuit

An electrical configuration containing two or more separate branches, where each branch experiences the same voltage across it.

Voltage in a parallel circuit

Remains identical across each individual branch, matching the full potential difference provided by the power supply.

Current in a parallel circuit

Splits among branches such that the total current entering the junctions equals the sum of the currents passing through each branch.

Ammeter

An instrument connected in series within a circuit path to measure the size of the electric current.

Voltmeter

An instrument connected in parallel across a power source or load to measure potential difference.

Short circuit

A pathway within a circuit that has little or no resistance, causing high current to bypass components and risk overheating.

Ohmic conductor

A device or material with a constant resistance whose voltage-versus-current graph displays a linear relationship.

Non-ohmic conductor

A device, such as a light globe or LED, with variable resistance that produces a curved voltage-versus-current graph.

Gradient of a voltage-versus-current graph

The slope ($\frac{\Delta V}{\Delta I}$) of a linear characteristic plot, which equates to the component's resistance ($R$).

Line of best fit

A straight or curved line plotted on a scatter graph that highlights the overall trend without necessarily passing through every data point.

Graphene

A single-atom-thick planar sheet of carbon atoms arranged in a hexagonal lattice, used to construct microscopic 2D circuits.

Independent variable

The condition or factor deliberately changed by the experimenter during an investigation.

Dependent variable

The factor measured or observed to assess the effect of the manipulated condition.

Controlled variable

A factor kept strictly constant throughout an experiment to prevent it from confounding the test results.

Control group

A baseline trial or setup kept without experimental manipulation to provide a benchmark for comparison.

Systematic error

A repeatable error caused by faulty calibration or improper use of equipment that biases measurements consistently high or low.

Random error

An unpredictable experimental variation caused by estimation or fluctuating conditions, minimized by averaging multiple trials.

Accuracy

The closeness of a measured experimental value to the true or accepted reference standard.

Precision

The degree of agreement and closeness among repeated independent measurements of the exact same quantity.

Reliability

The consistency and reproducibility of experimental measurements obtained across repeated trials.

Qualitative data

Descriptive, non-numerical observations recorded in an investigation, such as color changes or physical state.

Quantitative data

Numerical measurements and counts recorded during an experiment with explicit units.