In life sometimes there are moments when it is just necessary to learn tension operating in network immediately. For this purpose use the special device – the voltmeter. And how to determine tension if near at hand there is no voltmeter?
Instruction
1. It can be learned most, having used Om's law and using special formulas. The great physicist George Om is an author of the well-known law which sounds so: "Current in the site of a chain is directly proportional to tension, and is inversely proportional to the electrical resistance of this site of a chain izapisyvatsya by a formula: I=U/Rgde: I - current (A); U - tension (C); R - resistance (Ohm).
2. The fact that the law of Ohm is fundamentalnyyzakon is significant. Onprimenim to any system in which action of streams of particles or fields which overcome resistance takes place. He is quite applicable for calculation of pneumatic, hydraulic, magnetic, light, electric and heat fluxes.
3. George Om also found a formula for calculation of power in an electrical circuit: P=U*I, where P-power (W); U – tension (C); I – current (A).
4. Proceeding from this formula, it is easy to find tension. For this purpose: - take value of power of P; - divide it into value of current of I; The Value of power can be determined by the user's guide (passport) of the electric device which at you is involved in network. If several devices turn on, determine their total power which can be counted, having put capacities of all operating devices: P=P1+P2+ …. +Pn
5. The value of current can be learned also from the user's guide of the electric device or having measured it directly in network by means of the ampermeter. Measurement of current in a single-phase chain and three-phase is made equally.
6. To measure current: A) take the ampermeter; B) include it in one of phases of an electrical network; C) write down instrument readings. Now substitute the found values of power and current in a formula: U = P/I, gder – the power (W), I – current (A). Having substituted numerical values in a formula, find tension of U (B).