How Should an Ammeter Be Connected to a Circuit?
Ammeters are connected quite differently from the ways that voltmeters or ohmmeters are connected. For ohmmeters, the components must be isolated from both the circuit and the power. Voltmeters measure the potential difference between two points. Only the ammeter actually becomes part of the circuit it is measuring.
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Instructions
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Understand what it is that an ammeter is measuring--this will help you understand why an ammeter is connected the way it is. An ammeter is measuring the flow of current through the ammeter. The ammeter readout is telling you how many electrons are going through the ammeter per second. This is why an ammeter must be in the circuit it is measuring.
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Estimate the current limit. If your meter is set to measure a small current and you put a large current through the meter, it can be damaged.
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Put the ammeter in the circuit in the place you want to measure the current. This will mean cutting a wire and attaching the ammeter leads to the two cut ends. After you have made your measurement you will need to repair the cut wire.
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Tips & Warnings
It is often easier to measure the voltage and calculate the current. For example, if you want to know the current flowing through a 10k ohm resistor, you can measure the voltage drop across the resistor (without cutting any wires) and divide the voltage by 10,000 to get the amps.
To protect your meter, it is a good idea to always set the control switch to the highest amperage first, then click it down one level at a time until you get a reading. If you make this behavior a habit you will go through a lot fewer meters.
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