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, tells us how much energy is transferred for each unit of charge between two points. We measure it in volts, using V. A voltmeter measures voltage. Two circuits can have equal current but different voltages. The same amount of charge passes a point each second, but each unit transfers more energy at the higher voltage.
In one classroom test, Zara uses the same bulb and circuit. With one cell, the meters read 1.5 V and 1 A. With two cells, they read 3 V and 2 A. These are readings from this test, not fixed values for every bulb.
The two meters go in different places. An ammeter measures the flow, so it sits inside the path itself, wired in series, and every bit of charge passes through it. A voltmeter measures the difference between two points, so it sits alongside a component, wired in parallel, with one connection on each side of it.
An ammeter lets charge through very easily. If it is placed across a component, it becomes an easy path around that component. Most of the charge skips the component, so the reading is wrong and the current can grow large enough to be unsafe. A voltmeter lets almost no charge through. If it is placed in the loop, it nearly stops the current, so the bulb goes out.
Current is charge flow rate, measured in amperes with an ammeter in series. Voltage is energy transferred per unit charge, measured in volts with a voltmeter in parallel across a component.
Readings and flashcards were written for this topic.
The class torch got brighter the day Zara clipped in a second cell, and Omar drew the whole loop with proper symbols. Brighter is not a number, though. Zara puts two meters on the bench.
She starts with the ammeter, which measures the flow of charge. Where in the torch loop does it go?
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.