How to measure voltage and current
Using a multimeter:
When using multimeter, it is worth paying attention to a few basic issues:
- range of measured quantity – select a range larger than the expected measurement value, but the smallest possible (choosing too large a range will result in lower measurement accuracy) – for example, if you want to measure the voltage in a mains socket with an expected value of 230V and possible ranges of 2, 20, 200, 700 and 1000, the best choice would be the 700V range – is the smallest of the ranges greater than the expected value. When checking the voltage on a 9V battery, the best choice would be the 20V range, when checking the voltage on a 1.5V battery – range 2V.
- type of variability of the measured value – when measuring voltage or current, the type of variation is extremely important – measuring, for example, alternating voltage with a voltmeter adapted to direct voltage will result in an incorrect measurement result. Different multimeters use different symbols:
| Measured quantity and type of variability | Symbolic indication | Text tag |
|---|---|---|
| Constant voltage |  |
DCV |
| Alternating voltage |  |
ACV |
| DC | |
DCA |
| Alternating current | |
ACA |
How to measure voltage
Voltage is measured by connecting a voltmeter róparallel to the receiver:
How to measure current
Voltage is measured by connecting the ammeter in series with the receiver (very low internal resistance would cause a short circuit and permanent damage to the ammeter if it is connected in parallel with the receiver):
