Summary of How to Use a Multimeter
This article provides a beginner's guide to using a digital multimeter (DMM) for measuring voltage, current, and resistance. It explains dial settings like AC/DC voltage and amperage units, demonstrates correct probe placement (black to COM, red to Ω), and details the step-by-step process of measuring an AA battery's 1.5V DC output by connecting probes to the respective terminals.
Parts used in the Multimeter Guide:
- Digital Multimeter (DMM)
- Black Probe
- Red Probe
- AA Battery
A multimeter is a brilliant instrument that combines several functions – typically, measuring voltage, current and resistance. Although both digital and analogue multimeters exist, the vast majority in use today are digital and hence this guide will use images of a digital multimeter, or DMM, to illustrate various steps.
Getting Started With a Multimeter
To begin, let’s have a quick look at the multimeter and what all of those dials and symbols actually mean. Below are the basic settings options you will find on most DMMs:
- Voltage Type Selection – your DMM may be labelled with ‘V AC’ and ‘V DC’ to choose between alternating and direct current, or these may be represented with ‘V -’ (direct) and ‘V~’ (alternating).
- Amperage Unit of Measurement – you will normally be able to select to have the amperage shown in amps (A), microamps (uA) or milliamps (mA).
- Measuring Resistance – you will have an option to measure in ohms (Ω), the unit of resistance.
Now, let’s move onto the practical part! First, you need to plug your probes into the multimeter. Plug the black one into the COM (common) slot and the red one into the slot marked with the Ω symbol.
Be aware that the black probe is usually connected to ground or negative “-”, and the red one to power “+”. Don’t worry if you plug the black and red probes in the wrong slots, all that will happen is that you will get a negative reading.
How to Measure Voltage
We will take an AA battery as an example. Turn you DMM onto the DC voltage section. An AA battery voltage is approximately 1.5V, so turn your multimeter to 2V DC (slightly higher than you expect the reading to be).
Take your probes and place them against the positive and the negative terminals of the AA battery. Remember that your black probe should be on the negative terminal and the red on the positive one. You should see around 1.5V on your multimeter’s screen if you have a new battery.
That’s all there is to it – you have just measured the voltage of an AA battery! This theory remains the same for every device you want to test.
For more detail: How to Use a Multimeter
- What are the basic settings options found on most DMMs?
Basic settings include Voltage Type Selection (AC or DC), Amperage Unit of Measurement (amps, microamps, or milliamps), and Resistance measurement in ohms. - How do you plug the probes into the multimeter?
Plug the black probe into the COM slot and the red probe into the slot marked with the Ω symbol. - What happens if you plug the probes in the wrong slots?
You will simply get a negative reading. - Which section should you turn your DMM to for measuring an AA battery?
You should turn the DMM to the DC voltage section, specifically to 2V DC which is slightly higher than the expected 1.5V. - Where should the black and red probes be placed on an AA battery?
The black probe goes on the negative terminal and the red probe goes on the positive terminal. - What reading should you expect from a new AA battery?
You should see around 1.5V on the multimeter screen. - Does the theory for measuring voltage apply to other devices?
Yes, this theory remains the same for every device you want to test.
