Resistance is a certain ability of an element of an electrical circuit to interfere with passing on it electric current. It various materials, for example, copper, iron and nichrom possess. The general resistance is the resistance of all electrical circuit in general. It is measured in Ohms. It is necessary to know chain resistance for assessment of short circuit currents and the choice of switching devices.
It is required to you
- Ohmmeter, measuring bridge, calculator.
Instruction
1. For a start define how elements of an electrical circuit on the relation to each other as it influences calculation of the general resistance are connected. Conductors can be in consecutive or parallel connection. Consecutive connection is such connection when all elements are connected so that the site of a chain including them has no knot, and parallel connection is such connection when all elements of a chain are united by two knots and not have communications with other knots.
2. If you defined that conductors in an electrical circuit are connected consistently, it is possible to find full resistance. Just put resistance of all elements. If you were not given resistance of each conductor, but their tension and current of any element of a chain are given, then, having put all tension, you learn the general tension. Current of each element at consecutive connection are equal, that is and the general current is equal in all chain to the current of any conductor of this chain. And then, to find full resistance, divide the general tension into current.
3. If elements are connected in parallel, then the general resistance can be found the following method: multiply resistance of all conductors and divide into their sum. If you were not given resistance of each element, but are given them current and tension of any element of a chain, then, having put everything current, you recognize the general. Tension of each element at parallel connection is equal, that is and the general tension is equal in all chain to tension of any conductor of this chain. And then, to find full resistance, divide tension into the general current.
4. To determine the general resistance of an electrical circuit, use such measuring devices as an ohmmeter and the measuring bridge. They will help you to determine electric active resistance.