B.5.8—Circuit diagrams and conventional current

Read the circuit arrangement

A circuit diagram shows which components are connected in series and which share the same two nodes in parallel. Use the standard symbols supplied in the Physics data booklet; do not infer a connection merely because drawn lines cross unless a junction is shown.

Ideal meters

Place an ideal ammeter in series with the branch whose current is measured; its resistance is zero. Place an ideal voltmeter in parallel across the component whose potential difference is measured; its resistance is infinite. If a meter is stated to be non-ideal, use its stated constant resistance.

Conventional current

Conventional current follows the direction positive charge would move: through the external circuit from the source's positive terminal toward its negative terminal. In a metal, electrons drift in the opposite direction.

Common trap

Do not put an ideal ammeter directly across a source or an ideal voltmeter in series: those connections change or interrupt the intended circuit.