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Electric current and voltage

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# Measuring amps & volts

You need to know how to measure current and voltage.

## Current

Current is a measure of how much electric charge flows through a circuit. The more charge that flows, the bigger the current.

Current is measured in units called amps. The symbol for amps is A. For example, 20A is a bigger current than 5A.

### Measuring current

A device called an ammeter is used to measure current. Some types of ammeter have a pointer on a dial, but most have a digital readout. To measure the current flowing through a component in a circuit, you must connect the ammeter in series with it.

## Voltage

Voltage is a measure of the difference in electrical energy between two parts of a circuit. The bigger the difference in energy, the bigger the voltage.

Voltage is measured in volts. The symbol for volts is V. For example, 230V is a bigger voltage than 12V.

### Measuring voltage

Voltage is meaured using a voltmeter. Some types of voltmeter have a pointer on a dial, but most have a digital readout. To measure the voltage across a component in a circuit, you must connect the voltmeter in parallel with it.

Using a voltmeter to measure the voltage across a lamp

You can measure the voltage across a cell or battery. The more cells, the bigger the voltage.

The more cells, the bigger the voltage

## Checkpoint

Current Voltage
Measured in amps, A volts, V
Measured with ammeter in series voltmeter in parallel
Circuit symbol of measuring devise

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