To determine current power, take the ampermeter and the voltmeter, attach to the device consumer which power is measured, and, having taken readings, calculate its numerical value. When resistance of the conductor is in advance known, it is possible to measure only the current or tension and to count current power. She can also be recognized direct measurement.
It is required to you
- For carrying out measurements take the ampermeter, the voltmeter, a wattmeter, an ohmmeter.
Instruction
1. Direct measurement of power of current Take a wattmeter, attach it to the consumer on whom it is necessary to measure power. Connect its terminals to places of a conclusion of the consumer in network. On a scale analog or the screen of a digital wattmeter the power of this consumer will be displayed. Depending on settings of the device the value of power can be received in watts, kilowatts, milliwatts, etc.
2. Change of power with the voltmeter and the ampermeter Collect a chain, having included in it the consumer of electric current and the ampermeter. Attach the voltmeter parallel to the consumer. Connect measuring devices, observing polarity if a direct current. Start up electric current, having connected a source, and take readings of devices from the ampermeter value of current in amperes, and from the voltmeter value of tension in volts. Increase value of current by P=U•I. tension. The consumer's power in watts will be result.
3. Determination of power of current at the known resistance of the consumer If resistance of the consumer is known (find its value on the case or measure by an ohmmeter), and it is calculated on the known tension, then its rated power can be found, having squared this tension and having divided into value of resistance (P=U²/R). For example, at a bulb with a resistance of 484 Ohms and with a rated voltage of 220 V, power will be equal to 100 W. If tension of a source of current is not known, turn on consistently in the consumer's chain the ampermeter. Measure force of the current going through the consumer with his help. For calculation of power square current and increase by value of resistance (P=I²\• R). If current is measured in amperes, and resistance in Ohms, then the value of power will be received in watts.