Electricity

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The Voltage

How to measure a voltage

1) Multimeter and voltmeter

The voltage is measured using a voltmeter whose symbol is:


The multimeter can measure a current but it can also measure a voltage.
In this case we use the voltmeter mode.
   
2) How to connect a multimeter in voltmeter mode ?

- Terminals: We use the COM terminal and a voltage terminal (V)
- The sense of connection: The COM terminal is closest to the negative terminal and the voltage terminal closest to the positive terminal of the electric generator.
- The insertion in the circuit: The multimeter is connected in parallel (The multimeter is connected to the component's terminals for which we want to know the voltage).

3) How to choose the range for multimeter in voltmeter mode ?

Definition: The chosen range corresponds to the highest voltage that the voltmeter can measure.

The range used should not be smaller than the measured voltage: the measure couldn't be made and the voltmeter may be damaged.
The range should not be too great otherwise the measurement looses its accuracy.

Method: We must first use the highest range for an approximation of the voltage and then choose the closest (but higher) to obtain a more accurate measurement.

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