Voltmeter measures potential difference across its connection points Steps: - Identify circuit components: cell with EMF ε and internal resistance r, external resistor R, switch, voltmeter across R. - When switch open, no current flows, so potential difference across R is 0 V, not ε. - When switch closed, current I = ε / (r + R), terminal PD V = I R < ε due to voltage drop Ir across r. - Evaluate statements: A and B define EMF correctly as work per unit charge by cell; C states ε > V when current flows; D incorrectly claims voltmeter reads ε when open. Why D is correct: - Voltmeter reads PD across R; with open switch, I = 0, so V = 0, not ε (by Ohm's law, V = I R). Why the others are wrong: - A: Correctly specifies energy transfer per unit charge when current flows. - B: Accurately defines EMF as total energy per unit charge supplied by cell. - C: True, as ε = V + I r, so ε > V when I …