Measuring Electric Current in a Circuit

Steps:

• Recognize that the rate of flow of charge is electric current, measured in amperes.
• Identify the ammeter as the device that measures current.
• Note that to measure current through a resistor, the ammeter must be connected in series to include the resistor's current in the path.
• Confirm the setup ensures accurate reading without altering the circuit's total current.

Why B is correct:

• An ammeter measures current (I = Q/t, where Q is charge and t is time) and connects in series with the resistor to directly gauge the charge flow through it, per Ohm's law principles.

Why the others are wrong:

• A: Connecting an ammeter in parallel bypasses the resistor, causing a short circuit and incorrect readings.
• C: A voltmeter measures potential difference (voltage), not current, and parallels the resistor.
• D: A voltmeter in series disrupts current flow, as it has high resistance unsuitable for current measurement.

Final answer: B