For determination of resistance use the device which is called an ohmmeter. Attach it to the ends of the site of a chain and receive value of its resistance. Resistance can be measured, using the ampermeter and the voltmeter. Take readings from them and divide tension into current. It is possible to learn resistance of the conductor through its geometrical sizes and specific resistance of material.
It is required to you
- ampermeter, voltmeter, tables of specific resistance, roulette and caliper
Instruction
1. Determination of resistance by means of the ampermeter and the voltmeter Connect a chain to a current source. Consistently install in it the ampermeter and measure with its help current in amperes. To the interesting site of a chain in parallel attach the voltmeter and measure on it voltage drop in volts. During the work with a direct current observe polarity of devices. After readings are taken, divide value of tension into value of current. It will also be value of resistance of the site of a chain in Ohms.
2. Determination of resistance of the conductor with the help ommetrak to the ends of the conductor which is not connected to a current source attach an ohmmeter. The size of electrical resistance of this conductor will be reflected in the screen of the digital device or in a scale of the analog device.
3. Determination of resistance of the conductor Recognize material of which the conductor is made by material and the sizes and determine its specific resistance by the special table. Take result from a column where he moves in Om*mm2/m. After that measure length of the conductor in meters. For this purpose use a roulette. If the conductor has round section, measure its diameter in millimeters by means of a caliper and find cross-sectional area. For this purpose square diameter, divide into 4 and increase by 3.14. If a section form rectangular, then measure length and width of section in millimeters and multiply them. Often cross-sectional area is specified in the technical documentation of the conductor. To find resistance, divide length of the conductor into the area of its cross section, and increase result by specific resistance.