What is electrical power?

The work done by current per unit time is called electrical power; The unit time is seconds (s), and the work done refers to electrical work. Electrical power is represented by the uppercase English letter "P", which describes the physical quantity of the speed at which the current does work. The capacity of the electrical equipment usually refers to the size of the electrical power. It represents the ability of the electrical equipment to do work per unit of time.

If you don't quite understand, let's take an example: liken electric current to water flow. If you drink a large bowl of water once, the weight of the water you drink is the electrical work you do; And it took you a total of 10 seconds to finish drinking, so the amount of water you drink per second is the electrical power.

Electric power calculation formula

Through the basic description of the concept of electrical power above and the metaphor I have made, many people may have already thought of the formula for calculating electrical power; Let's continue to use the example of drinking water above to illustrate: since we drank a large bowl of water in a total of 10 seconds, it can be compared to doing a certain amount of electrical work in 10 seconds. Therefore, the calculation formula is obvious. Divide the electrical work by time, and the resulting value is the electrical power of the electrical device:

In the above calculation formula, P represents electrical power, and its magnitude depends on the product of voltage U and current I. The meanings represented by each letter in the above formula are as follows:

P - Electrical power, in watts

U - Voltage, in volts

I - Current, in amperes (A)

Q - Charge, unit (C) Coulomb

For conductor resistance, based on Ohm's law I=U/R, the electrical power consumed on the resistance can also be calculated using the following two formulas:

P=UI=U2/R, or P=I2R (because U=RI, then P=UI=R multiplied by I and then multiplied by I, all are I2R)

If you have paid attention to the comment on P in the above formula, you should already know that the name "electrical power" is represented by the letter P, and the unit of electrical power is represented by W (watt, abbreviated as W). Let's combine the above formula to understand how 1 watt of electrical power is obtained:

1 watt=1 volt × 1 Amp, or abbreviated as 1W=1V · A

In electrical engineering, the commonly used units of electrical power are kilowatts (KW): 1 kW=1000 W=103 W. In addition, in the mechanical industry, horse power is commonly used to represent the unit of electrical power. The conversion relationship between horsepower and electrical power units is:

1 horsepower=735.49875 watts, or 1 kW=1.35962162 horsepower;

In our daily electricity consumption and production, the commonly used unit of electrical work is the well-known "degree", where 1 degree of electricity represents the electrical energy consumed by an electrical appliance with a power of 1 kilowatt for one hour (1 hour), namely:

1 degree=1 kilowatt hour