Potentiometer as voltage divider Steps:

• Potentiometer divides supply voltage proportionally to wiper position along the resistive track.
• Assume 6 V battery across full track; P is midpoint (50% resistance), so voltmeter reads 3 V.
• Q is end of track (100% resistance), so voltmeter reads full 6 V.
• Polarity connection measures potential from wiper to common terminal, yielding increasing voltage from P to Q.

Why D is correct:

• Matches Ohm's law for voltage division: $V = V_{total} \times \frac{R_{wiper}}{R_{total}}$, giving 3 V at half and 6 V at full.

Why the others are wrong:

• A: Incorrectly assumes 0 V at P, ignoring partial division.
• B: Fails to increase voltage at Q, treating it as fixed midpoint.
• C: Wrongly sets P at 0 V (no division) but correctly identifies Q.

Final answer: D