Remember one rule when measuring: when measuring current, they are connected in series with the load, and when measuring other quantities, they are connected in parallel.

The figure below shows how to properly connect the probes and the load in order to measure the current:

We don’t touch the black probe that is plugged into the COM socket, but we transfer the red probe to the socket where mA or xA is written, where instead of x is the maximum current value that the device can measure. In my case, this is 20 Amperes, since 20 A is written next to the socket. Depending on what value of current you are going to measure, we stick a red probe there. If you don’t know how much current will flow in the circuit, then put it in the xA socket:

Let's see how it all works in action.In our case, the load is the fan from the computer. Our power supply has a built-in indication for showing the current strength, and as you know from the physics course, the current strength is measured in Amperes. We set 12 Volts, turn the knob on the multimeter to measure direct current. We set the measurement limit on the cartoon to 20 Amps. We collect as according to the scheme above and look at the readings on the cartoon. It exactly matched the built-in ammeter on.

To measure current AC voltage we put the multimeter's twist on the AC voltage measurement icon - "A ~" and in the same way we take measurements according to the same scheme.

How to measure DC voltage with a multimeter

Let's take this battery

As we can see, the current 550 mAh is written on it, which it can deliver to the load for an hour, that is, milliamps per hour, as well as the voltage that our battery has - 1.2 Volts. Voltage is understandable, but what is “current for an hour”? Let's say our load - a light bulb consumes a current of 550 mA. So the light will stay on for one hour. Or take a light bulb that shines weaker, and let it eat 55 mA from us, which means it can work for 10 hours.

The value of 550 mA, which we have written on the battery, is divided by the value that is written on the load and we get the time during which all this will work until the battery runs out. In short, who is friendly with mathematics, it will not be difficult for him to understand this miracle :-)

Let's measure the voltage on the battery, put one multimeter probe on plus and the other on minus, that is, we connect parallel, and voila!

In this case, the battery voltage is 1.28 volts. The value on a new battery must always be greater than what is written on the label.

Let's measure the voltage on the power supply. We set 10 volts and measure.

Red is plus, black is minus. Everything converges, the voltage is 10.09 volts. We write off 0.09 Volts for an error.

If we confuse the probes of the multimeter or the probes of the block, then nothing terrible will happen. The multimeter will show us the same value, but with a minus sign.

Keep in mind, this does not work on such multimeters

In order to accurately determine the polarity without a multimeter, you can resort to a few tips that are described in the article.

How to measure AC voltage with a multimeter

We set the limit for measuring alternating voltage on the cartoon and measure the voltage in the outlet. It doesn't matter how you stick the probes in. There is no plus or minus. There is a phase and zero. Roughly speaking, one wire in the outlet is not dangerous - this is zero, and the other can really spoil your well-being or even health - this is a phase.

In theory, the outlet should be 220 volts. But it shows 215 for me. There is nothing wrong with that. The voltage in the outlet "plays". Exactly 220 volts you are unlikely to see when measuring the voltage in the sockets of your house :-)