For reduction of current in an electrical circuit it is necessary to add additional resistance to a rupture of this chain. If exact change of size of current is required, determine parameters of a chain and carry out calculation of resistance for the law of Ohm.
It is required to you
- Multimeter, knife, screw-driver, resistance or bulb.
Instruction
1. The size of electric current in a chain depends on two parameters: tension and resistance. The easiest way of reduction of current is increase in resistance of an electrical circuit. For this purpose, previously executed gap joins the additional resistance or other device performing this function. Before performance of work make sure of safety of a workplace and lack of probability of defeat electricof current. Remember that all works connected with electric circuits should be carried out at the disconnected tension.
2. Switch off tension given on the scheme. For this purpose turn introduction the automatic machine or the switch to position "is switched off". Make sure by means of the indicator or a multimeter of the voltage measurement mode, of lack of tension in an electrical circuit. Measure resistance of an electrical circuit by means of a multimeter, having transferred it to the ohmmeter mode. In case of impossibility of this action the size of resistance can be determined, having summarized resistance of elements of a chain.
3. Calculate the required resistance of an electrical circuit under the law of Ohm. For this purpose it is enough to divide the enclosed tension into the required current size. It is necessary to subtract the measured resistance of an electrical circuit from the received value. The resulting size is resistance which should be added to a chain for decrease in current.
4. Pick up resistance with the size close to settlement. In the absence of the ready resistor, instead of it it is possible to use one or several glow lamps. Execute a rupture of an electrical circuit. For this purpose it is possible to cut one of the feeding wires by means of a knife or nippers. A knife smooth out the formed ends of wires. Attach these ends to output terminals of resistance or a bulb. Make sure of durability of connection of wires and the resistor or other device and also in lack of the bared parts able to lead to defeat by electric current. Give tension and check working capacity and operation parameters of the scheme.