Voltmeter measures PD across two cells in series

Steps:

• Identify circuit configuration: four 1.5 V cells likely form two parallel branches, each with two cells in series.
• Switch closure completes the circuit, allowing current flow.
• Voltmeter connects across one branch or equivalent two-cell PD.
• Calculate PD: two cells in series give 1.5 V + 1.5 V = 3 V.

Why C is correct:

• Voltmeter reads potential difference (PD) across two cells in series, where total PD = sum of individual cell voltages (Kirchhoff's voltage law).

Why the others are wrong:

• A: 0 V would indicate short circuit or open voltmeter path, not the case here.
• B: 1.5 V measures single cell, but voltmeter spans two.
• D: 4.5 V implies three cells in series, exceeding the two-cell span.

Final answer: C