you need
  • - Tester;
  • - documentation for consumers;
  • - current source.
To find amps , which is measured by the current, use a normal tester adjusted to measure this value.Turn it in series with the consumers.The display shows the current strength.If the tester is set to multiples or sub-multiples of the value, use the rules of translation into ordinary.For example, if the device in the chain shows the strength of the current is 120 mA, then divide that number by 1000 to get the value of 0.12 A. If the current is 2.3 kA, now multiply the value by 1000 and get 2300 A.
If you measure the strength of the current is not possible, find the voltage, which is necessary for the consumer, and its electr
ical resistance (Ohm's law for subcircuit).For this purpose the voltage on this portion of the chain U divide by the resistance R (I = U / R).For example, if a network connected household iron with a resistance of 160 ohms, the current it is the ratio of stress (in the home network, it is equal to 220) the resistance I = 220/160 = 1.375 A.
To determine the current in the circuit without measuring the voltage on the user to find out the emf (electromotive force) of the current source and the internal resistance.Determine the resistance of the circuit.Locate the amperage by dividing the sum of the internal EMF source resistance r, and external resistance R (I = EMF / (R + r)).For example, if the lamp is connected to a battery with emf 12, and has a resistance of 20 ohms, and the internal resistance of the battery is 4 ohms, the current in the lamp will be equal to I = 12 / (20 + 4) = 0.5 A.
Some appliances, such as lamps, indicated their power at the rated voltage.Determine the rated current that flows through such a device, the ratio of power P rated voltage U (I = P / U).For example, if the lamp specified, 100 W, 220 V, the current flowing through it will be equal to I = 100/220? 0.45 A.