POWER
(Or)
Definition of power It is the energy exchanged (given or received) by a body for one second.
Power rating Power is noted with the letter P.
Power unit The unit of power is the watt of symbol W.
The name of this unit was chosen in honor of the physicist James WATT.
It is also possible to use all the units derived from the watt like the milliwatt, centiwatt, deciwatt etc.
Among these derived units the most used in practice are:
》 The milliwatt: 1 watt = 1000 mW
》 The kilowatt: 1 kW = 1000 W
》 The megawatt: 1 MW = 1,000,000 W
》 The gigawatt: 1 GW = 1,000,000,000 W
Power and operation of a receiver The higher the power supplied to a receiver, the more efficient the operation of this receiver.
For example, a lamp shines more if it receives more electrical power. Rated power The nominal power corresponds to the electric power that a receiver must receive to operate under normal conditions.
The nominal power is the criterion which makes it possible to compare the performances of dipoles or electrical devices.
Example A 2000 W vacuum cleaner has better suction than a 1300 W vacuum cleaner A 600 W microwave oven heats food less quickly than a 1000 W microwave oven.
Link between voltage, current and power The electrical power (P) received by dipole depends on the voltage (U) and the intensity (I):
P = U x I In this relation P is expressed in watt, U in volt and I in ampere.
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