How to Measure the Current in a Parallel Circuit

Digital multimeter with ammeter function

Parallel circuits are composed of a power source, several electronic elements and the connections between the elements and the source. In this type of circuit, each element is connected across the source. This allows each element to receive full source voltage. Elements connected in this arrangement provide multiple paths for the current. As a result, each element can have a different amount of current flowing through it. The total current in the circuit is equal to the sum of the currents flowing through each element. Ammeters are electronic devices used to measure the amount of current flowing through these circuits.

Things You'll Need

• Ammeter

Instructions

1. Turn off the power to the circuit. Power supplies have two terminals when using direct current, positive and negative. Current will flow from negative to positive. Disconnect the wire connecting the circuit to the negative terminal of the power supply. All of the current flowing through this circuit comes through that particular wire. The objective is to force all of that current to flow through the ammeter before it enters the circuit.

2. Connect the negative terminal of the ammeter to the negative terminal of the power supply. Connect the positive terminal of the ammeter to the circuit wire that was disconnected from the power supply's negative terminal.

3. Set the ammeter on its highest current reading setting. This will help prevent damage to the meter. Turn the power supply back on. All of the current going into the circuit should be flowing through the circuit at this time. The ammeter will display some numbers that represent the amount of current flowing through the circuit. If the readings are too low, try reducing the current setting on the ammeter to get a better reading.

Tips & Warnings

• Do not use this method if the approximate amount of current flowing through the circuit is not known.

• Make sure that the ammeter chosen can handle the amount of current in the circuit.

References

• Regentsprep: The Parallel Circuit