Watt is a physical quantity that everyone has to deal with on a daily basis without even knowing it. What is measured by it, when did it arise, and by what formula can it be found? Let's find answers to all these questions.
What is a watt
First of all, it is worth knowing the definition of this term. So, watt is a unit of power used in the International System of SI.
It can be of three types:
- Mechanical.
- Electric.
- Heat.
It is generally accepted that 1 watt is the power at which work (A) of 1 joule is done in 1 second (t).
History of Appearance
Watts were first used as a measure of power in the UK in 1882. Before that, horsepower was in use, and in some countries their understanding was different.
The inventor of this unit of measurement (watt) was the "father" of the industrial revolution - James Watt (there is a spelling of Watt). In honor of him, by the way, she was named. For this reason, both the joule (named after the British scientist James Prescott Joule) and the watt are always capitalized when abbreviated.– W (in English W).
Since 1960, the watt has been a unit of power used throughout the world. After all, it was then that he was recognized by the SI system.
Power Formula
Having de alt with the definition and history of the appearance of a watt, it is worth knowing its formula. It looks like this: N=A / t. And it stands for work divided by time.
Sometimes, in order to find out the number of watts, a slightly different power formula is used: N=F x V. In this example, the desired value is calculated not using work and time, but using force and speed data.
In fact, the second formula is a kind of adaptation of the classical one. It is simply taken into account that the work is equal to the derivative of the force by the distance (A \u003d F x S), and the speed is the quotient of the distance divided by the time (V \u003d S / t). If you put all this data: you get the following example: N=F x S/t=F x V.
Watts, volts and amps
In addition to the formula considered in the previous paragraph for finding the physical quantity under study, there is another one. It shows the relationship between power (watts), voltage (volts) and current (amps).
However, it's worth learning a little more about these units before getting to know them.
Volt (V, in English V) is a unit of electrical voltage. In formulas, it is denoted by the Latin letter U.
Ampere (A, in English also A) - valuecharacterizing the strength of the electric current, denoted by the letter I.
The formula for the relationship between power, voltage and current
Briefly considering the features of all these quantities, we obtain this formula.
It looks like this: P=U x I. In it, P is power (watts), U is voltage (volts), I is current (amperes).
If necessary, this formula can be simulated if the power is already known, but you need to find the current (I=P / U) or voltage (U=P / I).
With the modern development of technology, in order to find out how many watts are contained in a certain number of amperes, you can simply find a specialized power calculation program on the Internet and enter the available data into it. It is not difficult to do this, in the line of any search engine you need to look for the phrase "watt to amp conversion calculator", and the system will give you the addresses of the sites you need.
Multiple Tues
Besides practical applications, the units in question are often used to make numerous theoretical calculations. However, if the power is extremely small, writing watts using decimals with many zeros is rather impractical. To facilitate this task, scientists introduced submultiple units of W. They are usually written as powers with a minus.
Today, a dozen of them have been allocated, but in practice, many of them are not used.
For example, the first two submultiples of a watt are: dW (deciwatt, equals 10-1 W) and cW (centiwatt, equals 10-2W) notrecommended for use. But milliwatt (mW, equals 10-3), microwatt (µW equals 10-6) and nanowatt (nW equals 10 -9W) are one of the most used. And not only in calculations, but also in the manufacture of various measuring instruments.
For example, medical devices such as electrocardiographs and electroencephalographs use microwatts (µW).
In addition to those listed above, there are five more submultiple units: picowatt (10-12), femtowatt (10-15), attowatt (10-18), zeptowatt (10-21) and ioktowatt (10-24). However, all of them are used in rare cases, and then only in theoretical calculations.
Divisions of Tue
The unit in question itself is relatively small. For example, to wash one kilogram of laundry in one hour in an automatic washing machine of class A ++, you need 150 watts of electricity. However, if we consider that on average about 3.5 kilograms of things are washed at the same time, then 525 watts are consumed. And this is just one wash, but how many of them happen in a month or a year? A lot, as well as the number of watts consumed. To make them easier to write, ten multiples of units are allocated based on W, written as degrees.
As with submultiples, the first two (decawatt - 101 and hectowatt - 102) are not accepted be used, so they only exist "de jure".
It is worth noting that when writing abbreviations of multiple units, often the first letters arecapital letters. This is done in order not to confuse megawatts (MW - 106) with microwatts (mW) and other similar values.
The most commonly used is the well-known kilowatt (kW). It is equal to one thousand watts (103). The second most popular is the aforementioned megawatt. This unit is most often used in the electric power industry. Less commonly, it uses such quantities as gigawatts (GW - 109) and terawatts (TW - 1012). For example, in one year, on average, humanity consumes about 1.9 TW of electricity.
The remaining four quantities are petawatts (PW - 1015), exawatts (EW - 1018), zettawatts (ZW - 10 21) and iottawatts (IVT 1024) are very rarely used, mainly in theoretical calculations. For example, according to one of them, it is assumed that the total power of the energy emitted by the Sun is 382.8 IW.
Despite the many multiples and submultiples of the watt, it is not difficult to perform mathematical operations with them. The easiest way is to convert everything to watts and then perform actions with degrees.
Another easy way to find out watts (the amount when using large or small quantities associated with them) is to find an online calculator on the Internet. By the way, with its help you can even convert watts into horsepower.
Watts and watt-hours
Having figured out what the watt unit is (as well as knowing its multiples and submultiples and finding formulas), it is worth taking the timeconsideration of such a close concept as watt-hours (Wh). Although the names of Tue and Wh are very similar, they mean slightly different things.
The second unit is used to measure the energy produced over a certain time period (one hour).
To make the difference more clear, it is worth considering the operation of an ordinary electric kettle with a power of 2200 watts. To prepare compotes for the winter, the hostess almost continuously heated water with it for one hour. During this time, the device used 2200 Wh. If a woman took a weaker 1100 W kettle, it would boil the same amount of liquid in two hours and still use the same 2200 Wh.
All electricity supplied to consumers is measured not in watts, but in watt-hours (more often in kilowatt-hours, also a ratio of one to a thousand). To confirm this, you can simply go to any house meter. Regardless of the country and manufacturer, next to the numbers (demonstrating the amount of electricity used) there will be a note “kilowatt-hour” (kWh). It can also be in English: kilowatt-hour (kW⋅h).
At the same time, the power of any power plant synthesizing it is measured in ordinary watts (kilowatts and megawatts).
