A complete circuit

Activity 3.6 gives you a cell, a lamp, holders and four wires. The book draws six ways of joining them. First predict which ones will make the lamp glow, then try them. Only two of the six work.

Compare the two that work with the four that don't. The lamp glows only when one terminal of the lamp is joined to one terminal of the cell, and the other terminal of the lamp to the other terminal of the cell.

That makes an electrical circuit: a complete path for the current, from the cell, through the lamp, and back to the cell. Any gap anywhere, and the current stops.

Remember to strip off about 1 cm of the plastic covering from each wire end. The plastic does not let current through, so a covered end is the same as a gap.

The direction of the current is taken to be from the positive terminal of the cell, round the circuit, to the negative terminal.