What a learner can do afterwards
- States that current is measured in amperes (A) and is the rate at which charge flows around a circuit
- States that potential difference (voltage) is measured in volts (V) and represents energy transferred per unit charge
- Correctly connects an ammeter in series and a voltmeter in parallel when building or interpreting a circuit
The lesson
Electric charge moves around a circuit like water moves through a pipe. Current tells you how much charge passes a point every second. We measure current in amperes, usually shortened to amps, using the symbol A. An ammeter is the tool that measures it.
Voltage, also called potential difference, is different from current. It measures how much energy each bit of charge carries as it moves around the circuit, not how fast the charge moves. We measure voltage in volts, using the symbol V. A voltmeter is the tool that measures it.
Zara builds a circuit with one bulb. With one battery, her voltmeter reads 1.5 V and her ammeter reads 1 A. She adds a second battery: the voltmeter now reads 3 V and the ammeter reads 2 A. The extra voltage pushes more current through the bulb, which is why it glows brighter.
Here is a way to remember it. An ammeter checks the flow, so it sits inside the path, in series. A voltmeter checks the difference between two points, so it sits alongside a component, in parallel.
Current, in amperes, is how fast charge flows and is measured with an ammeter in series. Voltage, in volts, is the energy each bit of charge carries and is measured with a voltmeter in parallel.
Watch it
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.