Ammeters measure current in series with components

Steps:

• Identify the resistor R in the circuit diagram.
• Locate meters: ammeters connect in series to measure current flow.
• Check each option's position relative to R.
• Select the ammeter directly in series with R.

Why D is correct:

• An ammeter in series with R measures the current through it, per Ohm's law (I = V/R), as it interrupts the path to quantify electron flow.

Why the others are wrong:

• A: Likely a voltmeter across R, measuring potential difference, not current.
• B: Positioned before/after the circuit branch, measuring total current, not specifically through R.
• C: Possibly in parallel or unrelated branch, bypassing R's current path.

Final answer: D