How is the total resistance in a series circuit determined?

The total resistance in a series circuit is determined by adding together the resistance values of each component connected in the circuit. This is because, in a series configuration, the electrical current has only one path to follow. Therefore, each resistor must be overcome sequentially, resulting in a total resistance that is the simple arithmetic sum of all resistances in the circuit.

When resistors are connected in series, the resistance increases as more resistors are added. This relationship is crucial in circuit design, as it directly affects the amount of current flowing through the circuit, dictated by Ohm's law (V = IR, where V is voltage, I is current, and R is resistance). Understanding this helps ensure that electrical systems operate safely and effectively by managing resistance levels appropriately.

The other choices do not accurately represent how total resistance is calculated in a series circuit. Voltage supply contributes to the overall circuit behavior but does not influence the total resistance directly. Relying on only the longest resistor or averaging resistances would misrepresent the sum of all resistances, leading to inaccurate assessments of the circuit's total resistance.