Circuit fundamentals
Charge, potential difference, resistance, and the circuits that make them work together.
Read in order
- What voltage meansA battery can have a voltage across its terminals even when nothing is connected. What is voltage, and why is it the quantity that makes charge transfer possible?
- What current measuresVoltage tells us energy per charge, but a circuit also needs a rate. What exactly does current measure, and why can the same current be described even though electrons move slowly inside a wire?
- Why resistance changes currentIf voltage is energy per charge and current is charge per time, what property of a component links them, and when is the simple rule V = IR allowed?
- Series and parallel circuitsA circuit can keep one path or split into branches, yet charge cannot disappear at a junction. What stays the same in series and parallel, and how can a network become one equivalent resistance?
- What electrical power measuresVoltage tells us energy per charge and current tells us charge per time. What rate of energy transfer appears when both act together, and how does it become heat or stored energy?
- How to measure a circuitA multimeter can report voltage, current, and resistance, but its connections change the circuit. How do you measure each quantity without asking the instrument to make a dangerous circuit?