Which device should be connected in series to measure current?

Which device should be connected in series to measure current?

• A. Ammeter
• B. Voltmeter
• C. Multimeter
• D. Oscilloscope

Answer: (A)

Current measurement requires placing the instrument in series so the same current flows through it. An ammeter is built for this role and is connected directly in the path of the circuit; its very low internal resistance means it introduces only a tiny voltage drop, so it doesn’t noticeably alter the current you’re trying to measure. If you tried to put a voltmeter in series, its high internal resistance would greatly restrict the current and distort the reading, which is why it’s designed to be connected in parallel across a component to measure voltage, not in series. An oscilloscope is typically used to observe voltage signals and is connected in parallel with the circuit, usually to a high-impedance input so it doesn’t load the circuit; it’s not used for measuring current in series. A multimeter can measure current when placed in series and set to current mode, but the instrument specifically intended for straightforward, minimal-disturbance series current measurement is the ammeter.

Current measurement requires placing the instrument in series so the same current flows through it. An ammeter is built for this role and is connected directly in the path of the circuit; its very low internal resistance means it introduces only a tiny voltage drop, so it doesn’t noticeably alter the current you’re trying to measure.

If you tried to put a voltmeter in series, its high internal resistance would greatly restrict the current and distort the reading, which is why it’s designed to be connected in parallel across a component to measure voltage, not in series. An oscilloscope is typically used to observe voltage signals and is connected in parallel with the circuit, usually to a high-impedance input so it doesn’t load the circuit; it’s not used for measuring current in series. A multimeter can measure current when placed in series and set to current mode, but the instrument specifically intended for straightforward, minimal-disturbance series current measurement is the ammeter.