A student connects a battery to two identical resistors in a parallel circuit. Explain why the total resistance of the parallel circuit is less than the resistance of just one of the resistors, and describe what happens to the total current from the battery compared to a circuit containing only one of those resistors connected to the same battery.

In a parallel circuit the battery voltage is applied to each resistor, so the potential difference across each branch is the same.
1. The current from the battery therefore splits, flowing through both resistors simultaneously.
2. Because there are two paths, charge can flow more easily; the overall opposition to flow is reduced.
3. The equivalent resistance of two equal resistors in parallel is R/2, which is less than the resistance of one resistor alone.
4. The lower total resistance means, by Ohm’s law (I=V/R), that the current supplied by the battery increases.
5. Thus the total current from the battery is greater than the current that would flow if only one of the resistors were connected.