Fundamentals of Electric Current and Circuits

Current

Flow of electric charge, measured in amperes (A).

Potential difference (voltage)

Energy transferred per unit charge, measured in volts (V).

Resistance

Opposition to current flow, measured in ohms (Ω).

Ohm's Law

V = IR.

Series circuit current distribution

Same at all points in the circuit.

Series circuit voltage distribution

Shared across all components.

Parallel circuit current distribution

Shared between branches.

Parallel circuit voltage distribution

Same across all branches.

Voltmeter symbol

Circle with a "V" inside - connected in parallel.

Ammeter symbol

Circle with an "A" inside - connected in series.

Required practical for electricity

Measure current & voltage across a component; plot V‑I graph to find resistance.

Potential difference

the difference in the amount of energy that charge carriers have between two points in a circuit.