purpose. It has a current-sensing element similar to clamp-on ammeters, but produces a chart or graph showing current changes over time.
Voltmeters The unit of electromotive force (EMF) is the volt (V). One volt is the pressure that, if applied to an electrical circuit having a resistance of 1 Ω, produces a current of 1 A. Connect a voltmeter across the terminals at the place where the voltage is to be measured, as shown in Figure 1-3. Never connect a voltmeter across a circuit with a voltage higher than the rating of the instrument. Doing so can damage the meter, or in extreme cases cause the voltmeter to explode.
DC Circuits When measuring voltage in a DC circuit, always observe proper polarity. The negative lead of the voltmeter must be connected to the negative terminal of the DC source, and the positive lead to the positive
1-3 Connecting a voltmeter to a circuit. 6
