A student sets up a series circuit containing a battery, two resistors and an ammeter. The student then sets up a parallel circuit using the same battery and the same two resistors, with a voltmeter connected across one of the resistors. Explain the differences the student would observe in the ammeter readings and the voltmeter readings between the two circuits.

In the series circuit the two resistors are in one path, so the same current flows through both. The ammeter therefore reads the current that flows through the whole series chain, which is relatively small because the total resistance is the sum of the two resistances.

When the same two resistors are connected in parallel, the battery sees two parallel paths. The total resistance is lower than either resistor alone, so the battery supplies a larger total current. The ammeter, which measures the total current leaving the battery, will read a higher value than in the series set‑up.

In the series circuit the battery voltage is divided between the two resistors. The voltmeter, if connected across one resistor, will read only the voltage drop across that resistor, which is less than the full battery voltage.

In the parallel circuit each resistor is directly across the battery terminals. The voltmeter across one resistor therefore measures the full battery voltage. Consequently the voltmeter reading in the parallel circuit is higher than the reading across the same resistor in the series circuit.