Physics

Circuits

Proton charge

The fundamental relative electrical charge assigned to a single proton, equal to positive one (+1). This positive charge is balanced by orbiting electrons in a neutral atom and resides firmly within the atomic nucleus.

Electron charge

The fundamental relative electrical charge assigned to a single electron, equal to negative one (-1). This negative charge creates electrostatic interactions that bind electrons into shells around the positive nucleus.

Neutron charge

The electrical charge of a neutron, which is exactly zero (0) because it is electrically neutral. Neutrons contribute mass and nuclear stability without altering the net electrical charge of an atom.

Net charge

The overall electrical charge of an object, determined by calculating the mathematical imbalance between its total number of protons and electrons. If an object has more electrons than protons, it possesses a negative net charge; if it has fewer, its net charge is positive.

Law of electrostatic charges

The fundamental physical principle stating that like charges repel each other, while opposite charges attract each other. For instance, two positive charges push apart, whereas a positive and negative charge pull together.

Charging by friction

A method of static electrification where two different insulating materials are rubbed together, causing physical contact that strips electrons from one material and deposits them onto the other. The material gaining electrons becomes negatively charged, while the material losing them becomes positively charged.

Charging by induction

The process of redistributing electrical charge on a neutral conductor by bringing a charged object close to it without making physical contact. The presence of the external charge repels or attracts free electrons within the conductor, polarizing opposite charges to different sides.

Charging by contact

A static charging method where a charged object touches a neutral object, allowing direct physical transfer of electrons until charge is shared or balanced between them. Both objects end up with the same type of static charge.

Electrical discharge

The sudden, rapid transfer or release of accumulated excess static electric charge off an object. It typically occurs when the electric field becomes strong enough to ionize surrounding air molecules, allowing electrons to jump across a gap in a spark to restore neutral equilibrium.

Grounding (earthing)

The safety procedure of connecting an electrical conductor or metal object directly to the Earth using a low-resistance copper wire. This provides a safe pathway for excess static electrons to drain away into the ground, preventing dangerous shock or spark hazards.

Lightning formation

An atmospheric electrostatic discharge phenomenon where vigorous ice particle collisions inside storm clouds separate charges, accumulating positive charges at the top and negative charges at the base. This negative base induces a positive charge on the ground below, eventually triggering a massive spark discharge of lightning between cloud and earth.

Conductor

A material, such as copper or aluminum, that permits electric current to flow easily through it. Structurally, conductors contain delocalized outer electrons in metallic bonds that are free to move throughout the lattice structure when voltage is applied.

Insulator

A material, such as plastic, rubber, or glass, that resists the flow of electric current. Its atoms hold electrons tightly in fixed covalent or ionic chemical bonds, preventing any free movement of charge and making it ideal for safety coverings on wires.

Lightning rod

A protective metal rod installed at the highest point of a building and connected to heavy copper grounding cables leading deep into the Earth. It provides a safe, low-resistance conduction pathway that intercepts lightning strikes and diverts the massive electrical energy harmlessly into the ground.

Closed circuit

An unbroken, complete electrical loop that allows electric current to flow continuously from the power source through components and back. Every part of the pathway must be conductive and connected for current to circulate.

Open circuit

An incomplete electrical pathway that contains a break, a gap, or an open switch, which completely halts the flow of electric current. Because the loop is broken, electrons cannot travel around the circuit.

Electron flow

The actual physical movement of negatively charged electrons through the conducting wires of a circuit, moving strictly from the negative terminal to the positive terminal of a power source.

Conventional current

The historical model of electric current direction defined to flow from the positive terminal of a power source around the circuit to the negative terminal. It flows in the opposite direction to actual physical electron flow.

Battery

An electrochemical power source that utilizes internal chemical reactions to create a potential difference between its positive and negative terminals. This voltage difference creates an electric field that pushes electrons through an external circuit.

Current

The rate of flow of electric charge past a specific point in a circuit, denoted by the symbol I and measured in Amperes (A). It represents how many coulombs of charge pass per second and is measured using an ammeter connected in series.

Voltage

The electrical potential difference or push per unit charge provided between two points in a circuit, denoted by V and measured in Volts (V). It represents the energy supplied to drive electrons through components and is measured using a voltmeter connected in parallel.

Resistance

The opposition offered by a component or wire to the flow of electric current, denoted by R and measured in Ohms. Higher resistance restricts current flow, converting electrical energy into heat or light energy within components like resistors and bulbs.

Electrical energy

The total work done or energy transferred by an electric current flowing through a circuit over a given time period, measured in Joules (J). It can be converted into thermal, light, or kinetic energy by circuit loads.

Ammeter

A diagnostic measuring instrument that must be connected directly in series within a circuit branch to measure electrical current in Amperes (A). It has very low internal resistance so it does not alter the current it is measuring.

Voltmeter

A measuring instrument connected in parallel across a specific electrical component to measure its voltage drop in Volts (V). It possesses extremely high internal resistance to ensure minimal current diverts through the meter.

Series circuit

A single-loop electrical circuit where components are connected sequentially, meaning current is identical at all points (I total = I1 = I2) and total source voltage is shared across components (V total = V1 + V2).

Parallel circuit

An electrical circuit featuring multiple branch pathways, meaning voltage is uniform across all branches (V total = V1 = V2) and total current splits across the branches (I total = I1 + I2).

Ohm's Law

The fundamental mathematical relationship in electronics stating that voltage equals current multiplied by resistance, expressed as V = I * R. It allows you to calculate unknown voltage, current, or resistance values in circuit components.

Factors affecting wire resistance

The physical properties that determine a wire's resistance, which include its length (longer wires increase resistance due to more lattice collisions), its thickness or cross-sectional area (thinner wires increase resistance by restricting pathways), and its temperature (higher temperatures increase resistance due to violent atomic vibrations).