Experts know that it is the simplest to find chain resistance by means of the special device of an ohmmeter. But what to do if for any reason of this device is not present near at hand, or connection it is impossible? In these cases it is necessary to resort to alternative methods of stay.
It is required to you
- - ohmmeter;
- - ampermeter;
- - voltmeter;
- - caliper.
Instruction
1. Determine resistance by means of an ohmmeter. Take an ohmmeter and attach it to the ends of the conductor which is not connected at the same time to a current source. Look at the device dial. The size of resistance of this site of a chain will be reflected in a scale of the device or in a digital board.
2. Determine resistance by means of the ampermeter and the voltmeter. Measure resistance moment by means of the ampermeter and the voltmeter if you have no ohmmeter. For this purpose perform the following operations. Connect a chain to a current source.
3. Install consistently by the ends of a chain the ampermeter and in parallel to the measured site – the voltmeter. At connection of devices it is necessary to observe polarity: contacts are connected positive to positive, negative to negative.
4. Take readings of devices which will appear on the screen. Do not forget that the voltmeter outputs indications in volts, and the ampermeter in amperes.
5. Find the moment of resistance of network. For this purpose divide value of tension into value of current. As a result receive value of resistance in Ohms.
6. Determine resistance by means of material and the size of the conductor. Learn of what material the conductor consists. Determine its specific resistance, using the special table which without effort can be found in the Internet. At the same time it is necessary to take result from that column of the table where it moves in Om*mm2/m. Measure length of the conductor in meters.
7. Determine the cross-sectional area of the conductor. For this purpose it is possible to use a caliper if the conductor has round section. In a case with round section it is necessary to learn diameter in millimeters, and after to find the area of its cross section: diameter is squared, divided into 4 and is multiplied by 3.14.
8. If section has other form, for example, a rectangle, all the same find its area if it is not specified initially for the concrete conductor. Do it on the corresponding formulas for each of specific forms of section.
9. Increase the received specific resistance by length of the conductor and divide into the area of its cross section. The moment of resistance is found.