Not always near at hand there is an ohmmeter. If it is absent, it is possible to measure loading resistance in the indirect way - on the current passing through it. Tension on it in many cases is already known.
Instruction
1. Power off loading.
2. Disconnect from loading that from wires of the power supply which is not connected to its general wire.
3. Connect one of probes of the ampermeter or the multipurpose measuring device (tester, a multimeter) working in the corresponding mode to the disconnected power supply conclusion, another - to the disconnected loading conclusion. If it eats a direct current, observe at the same time polarity.
4. As the switch on the measuring device choose a current sort (variable or constant) and also the range which is approximately corresponding to the current consumed by loading. If necessary, rearrange plugs on the device in the nests corresponding to a sort of current and range.
5. Include loading food, wait for completion of transition processes, read indications of the indicator of the measuring device, remember or write down them, and then power off loading.
6. Transfer result of measurement to the SI system. Loading supply voltage (it is supposed that it is known in advance) also transfer to it a system. Divide tension into current. You receive the value of resistance expressed in ohms. If necessary, transfer it to kilohms or megaohms.
7. In case it is necessary to measure loading resistance in the set mode, use this method even in the presence of an ohmmeter. For example, if to measure by an ohmmeter resistance of the switched-off glow lamp, then it will be known what it is in switched off, but not in the included state. However, it is known that at warming up it considerably increases. What it will become after thread of a lamp is warmed, it is possible only in the indirect way described above. Consider, however, that starting current of many loadings is exceeded considerably by the worker. If the measuring device is not calculated on such current, connect parallel to it before measurement well isolated switch. Before inclusion of loading close the measuring device the switch and when loading comes to an operating mode - open.