Correct Circuit for Measuring Current and PD Across a Resistor

Steps:

• Identify ammeter placement: connect in series with the resistor to measure current flow through it.
• Identify voltmeter placement: connect in parallel across the resistor to measure potential difference.
• Ensure power source completes the circuit without altering resistor connections.
• Verify no short circuits or incorrect meter placements that would bypass measurements.

Why A is correct:

• Ammeter in series measures current (I) via Ohm's law (V = IR), while voltmeter in parallel directly reads PD (V) across the resistor.

Why the others are wrong:

• B: Ammeter in parallel shorts the resistor, giving incorrect current reading.
• C: Voltmeter in series disrupts current flow, yielding zero or erroneous PD.
• D: Both meters incorrectly placed, measuring unrelated quantities like source PD or total current.

Final answer: A