--- title: "Current, voltage, and what they measure" description: "Understand current as charge flow rate and voltage as energy transferred per unit charge, then connect each quantity to its meter and circuit connection." canonical: https://lightmysky.com/learn/science/current-voltage-and-what-they-measure-mt_2bnXrfS4Iq source: https://lightmysky.com/learn/science/current-voltage-and-what-they-measure-mt_2bnXrfS4Iq.md retrieved: 2026-10-19 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Current, voltage, and what they measure Understand current as charge flow rate and voltage as energy transferred per unit charge, then connect each quantity to its meter and circuit connection. Subject: Science · Area: Energy · Ages 11 to 12 Page: https://lightmysky.com/learn/science/current-voltage-and-what-they-measure-mt_2bnXrfS4Iq ## Ready when they can - 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 ## Lesson: Current, voltage, and what they measure 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. *(drawing: An ammeter measures current. Bulb A has 1 amp flowing through it. Bulb B has 3 amps, so more charge passes through Bulb B every second.)* 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. **Example.** 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. *(drawing: Ammeter in series, inside the loop. Voltmeter in parallel, with one clip on each side of the part it checks.)* 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. **Recap.** 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. ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Circuit vocabulary](https://lightmysky.com/learn/science/circuit-vocabulary-mt_NzCNuABT3E) - [Drawing circuits with proper symbols](https://lightmysky.com/learn/science/drawing-circuits-with-proper-symbols-mt_NzNLYDb9CZ) - [More batteries, brighter bulb](https://lightmysky.com/learn/science/more-batteries-brighter-bulb-mt_vFT_GbkP9m) ## Opens up - [Static electricity and sparks](https://lightmysky.com/learn/science/static-electricity-and-sparks-mt_2_YoprauaJ) - [Electromagnets](https://lightmysky.com/learn/science/electromagnets-mt_2qkn8Lhc8e) - [Electromagnetic induction and generators](https://lightmysky.com/learn/science/electromagnetic-induction-and-generators-mt_e0jgUKANT-) - [Ohm's Law: voltage, current, resistance](https://lightmysky.com/learn/science/ohms-law-voltage-current-resistance-mt_H3ZDK0EYNV)