A multimeter also referred to as volt-ohm meter or VOM, is a handheld gadget that measures AC/DC voltage, current, and resistance in electronic circuits. Other advanced units test continuity, diodes, capacitance, frequency, temperature, and many more. Multimeters are small, lightweight, and run on batteries. They also come in two versions which are digital and analog multimeter versions. As a matter of fact, they are one of the most preferred tools by electricians to troubleshoot electrical issues on power supplies, motors, circuits, wiring systems, and appliances.
Apart from being used by professionals, DIYers can as well learn how to use multimeters at home. Digital multimeters are the best to use as they are easy to read and very accurate. The key uses of a multimeter are to measure volts, ohms, and amps.
Summary of Contents
What is a multimeter?
A multimeter is a device that is used to measure electricity. But unlike other tools, it can measure different things, and that’s where it derives its name “multimeter,” meaning a multi-tool. Almost all multimeter models can measure voltage, current, and resistance. But some advanced multimeters can do more than that.
What are voltage, current, and resistance?
In order for you to use a multimeter accurately, you need to know the symbols on the multimeter and how to use it. These include locating the dial, knob, ports, and test leads. The three basic functions have been explained further as follows:
- Voltage – is how hard electricity is being pushed via a circuit. A greater voltage means the electricity is being pushed harder. Normally, voltage is measured in Volts, and its symbol is V.
- Resistance – is how hard it is for electricity to flow via something. Higher resistance means that it is extremely hard for electricity to flow. The symbol for resistance is Ω, and it is measured in ohms.
- Current – is how much electricity is flowing through a current. If the current is high, this means more electricity is flowing through. A is the symbol for amperes, in which the current is measured.
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A simple way to understand voltage, current, and resistance is by taking the example of water flowing through a pipe. The current can be taken to be the water flowing through the pipe. The voltage is like the amount of pressure making the water flow. And finally, resistance is like an obstruction inside the pipe. So, a pipe that is clogged with debris may have an interrupted flow and will have greater resistance than a pipe with no obstruction.
Note that a direct current (DC) constantly flows in one direction, while an alternating current (AC) is the current that changes ways, normally several times in just one second.
Some Practical Uses of a multimeter
- Spot the hot wire: if you switch the light on/off, the light fixture on the ceiling doesn’t work. To fix the light switch, you need to switch off the power at your main breaker panel. Take a look inside the box by pulling the connected switch out carefully and then measure AC voltage and its range to 200 volts. This procedure will let you know if power is reaching the switch.
- Inspect extension cords: you can use a multimeter to test the dusty or worn-out extension code. Set the multimeter dial to its continuity test mode. Search for the soundwave symbol and turn on the multimeter. If you hear a beeping or tone sound for all three receptacle pairs, then it is good to go.
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- Detect a bad switch: if you suspect your light switch to be bad, you can use a DMM to find out. Just switch off the power at the panel and disconnect the switch from wiring in its electrical box. Then, use the probes to test. If the light switch is okay, the device will read a resistance value close to zero. But if it still shows “OL” or infinite resistance, then there is a high chance that the switch is bad.
- Test batteries: if you come across batteries that have not been in use for over a long period of time, you can test the batteries using a multimeter to know if they are still functioning.Set it to 20 volts. Switch the multimeter dial to the DC voltage position. If you see 1.5 volts, then the battery may still be alive. But if it shows “OL,” then the voltage range is too low, and the battery may be bad.
- Test bulbs: you can determine if some old bulbs in your house are good or not by using a multimeter. Set the meter to continuity test and switch it on. Have a person hold the bulb as you carry out the test.
With a multimeter, you can measure different electrical appliances in the house, power outlets, car batteries, and many other electrical circuits and components. Use a digital multimeter to measure voltage, current, and resistance. But if you’re a pro, you can go for the advanced multimeter to measure other tests as well. Always go for the high-quality and reliable multimeter brands like Fluke, Klein, Etekcity, INNOVA, and Amprobe.