Electricity & Circuits
11 concepts in Physics
Electricity and circuits explore how electric charge flows through conductors and how we harness that flow to power everything from light bulbs to computers. Students learn the foundational quantities — charge, current, voltage, and resistance — and discover how they relate through Ohm's law. They study series and parallel circuits, learning to predict how adding components changes the behavior of the whole system. Circuit diagrams provide a universal language for representing electrical systems. Electrical power and energy calculations connect circuit theory to real-world concerns like household electricity bills and device ratings. Understanding circuits is essential for physics, engineering, and everyday technological literacy, and it provides the conceptual bridge to more advanced topics in electromagnetism and electronics.
Suggested learning path: Start with electric charge and current as the flow of charge, then study voltage and resistance, apply Ohm's law, and build understanding of series and parallel circuits before exploring electrical power.
Electric Charge
A fundamental property of matter that causes it to experience a force in an electromagnetic field. Measured in coulombs (C).
Electric Current
Electric current is the rate at which electric charge flows past a point in a circuit or conductor.
Voltage
The difference in electric potential energy per unit charge between two points. Measured in volts (V).
Resistance
A measure of how strongly a material opposes electric current, measured in ohms ($\Omega$) — higher resistance means less current for a given voltage.
Ohm's Law
The fundamental relationship stating that the voltage ($V$) across an ohmic conductor equals the current ($I$) flowing through it multiplied by its resistance ($R$).
Circuit
An electrical circuit is a closed path through which electric current flows from a power source, through components, and back to the source.
Series Circuit
A circuit arrangement in which components are connected end-to-end along a single path, so exactly the same current flows through every component.
Parallel Circuit
A parallel circuit connects components in separate branches between two common nodes, so each component gets the full source voltage.
Circuit Diagram
A simplified drawing of an electrical circuit using standardized symbols for components like batteries, resistors, switches, and bulbs.
Kirchhoff's Laws
Kirchhoff's laws are two rules for analyzing circuits. Kirchhoff's current law says current is conserved at a junction, and Kirchhoff's voltage law says the total.
Electrical Power
The rate at which electrical energy is converted to other forms of energy (heat, light, motion). Measured in watts (W).