An ammeter is a measuring device used to measure the electric current in a circuit. A voltmeter is connected in parallel with a device to measure its voltage, while an ammeter is connected in series with a device to measure its current.

The conductor runs a circular path from the power source, through the resistor, and back to the power source. The power source moves the existing electrons in the conductor around the circuit. This is called a current. Electrons move through a wire from the negative end to the positive end.

Electricity Vocabulary

A voltmeter is used to measure potential difference across two points in an electrical circuit. When ammeter is connected in parallel to the circuit, net resistance of the circuit decreases. Hence more current is drawn from the battery, which damages the ammeter.

Voltmeter has high resistance because it measures the voltage difference between two different points, but it should not change the amount of current going through the element between those two points .

A voltmeter has high resistance so as not to burden the circuit you are measuring. Adding the meter into the circuit changes the circuit and thus changes the value you are trying to read. The higher the resistance (impedance) of the meter, the less the circuit is affected.

The resistance of a voltmeter is very high and for an ideal voltmeter, its value is infinity.

Just like voltmeters, ammeters tend to influence the amount of current in the circuits they’re connected to. However, unlike the ideal voltmeter, the ideal ammeter has zero internal resistance, so as to drop as little voltage as possible as current flows through it.

The reason for ammeter resistance to be low is because it can accurately read the current flowing in the circuit. When the ammeter resistance is low, almost all the current in the circuit is allowed to pass through the ammeter. This is because, in this case, the ammeter itself would oppose the flow of current.

The resistance of an ideal ammeter should be zero. This is because an ammeter is connected in series in a circuit. This would decrease the amount of current flowing through the circuit. Hence, in order to avoid the change of current flowing in a circuit.

Since the ammeter and the voltmeter are in parallel the voltage seen in the voltmeter is the same on both devices, and the ammeter will show the current that flows through it so that we can use Ohm’s Law to find it’s resistance: R=V/I.

Multimeter Tutorial Includes: One important measurement that can be made with a multimeter is a resistance measurement. Not only can these be made to check the accuracy of a resistor, or check it is functioning correctly, but resistance measurements can be required in many other scenarios as well.

240 Ω

240 ohms

For example, a 100 watt light bulb operating on 120 volts AC will have 144 ohms of resistance and will draw 0.833 Amps.