Watt - unit of power

Watt – it is a physical quantity with which everyone has to face on a daily basis, without even knowing it. What it measured when it originated and by what formula can find her? Let's find the answers to all these questions.

What is a watt

First of all, you should know the definition of the term. So, watt-the unit of power used in the International system of units.

It can be of three types:

• Mechanical.
• Electrical.
• Heat.

It is considered that 1 watt is such a power that in 1 second (t) is the work (A) to 1 Joule.

Appearance

The First time watts was used as the measure of power in the UK in 1882 Before the move was horsepower, and in some countries their understanding is different.

The Inventor of this unit (watt) became the “father” of the industrial revolution-James Watt (found spelling watt). In honor of him, by the way, she was named. For this reason, as the Joule (named by name the British scientist James Prescott Joule) and the watt, abbreviated is always written with a capital letter-W (English W).

Beginning in 1960 watt-unit of power used throughout the world. Because it was then recognized by the SI system.

Power Formula

Having dealt with the definition and history of watt, is to know its formula. It looks this way: N = A/t. And it stands for as work divided by time.

Sometimes in order to know how many watts the power formula uses slightly different: N = F x V. In this example, the desired value is calculated not by the work and time, and using the data of power and speed.

In fact, the second formula is a unique adaptation of the classic. Just take into consideration that the work is equal to the derivative of force over a distance (A = F x S), and speed is the quotient of distance by time (V = S/t). If you put all these data: it turns out this example: N = F x S/t = F x V.

Watts, volts and amps

In Addition to discussed in the preceding paragraph formula to search for the studied physical quantities, there is another. It shows the relationship power (watts) voltage (volts) and current (amperes).

However, before you read it, you should know a little more about these units.

Volt (V. V) – a unit of electrical voltage. In the formulas denoted by the letter U.

Amps (And English too well) – the value characterizing the strength of the electric current, denoted by the letter I.

Formula of the relationship between power, voltage, and current

Briefly examined the features of all these quantities, we obtain the given formula.

It Looks so: P = U x I. It R -; power (watts), U-voltage (volts) I-current (amps).

If necessary this formula can be modeled if the capacity is already known, but need to find the amperage (I = P / U) or voltage (U = P/ I).

The modern development of technology, in order to know how many watts are contained in a certain number of amps, you can just find on the Internet specialized program calculate power and enter the available data. To make it easy, in the line of any search you need to search for the phrase ‘calculator transfer watt per amp", and the system will give the addresses of relevant websites.

Decimal Fraction units W

In Addition to practical application, these units are often used for work in numerous theoretical calculations. However, if the capacity is extremely small, record watts using decimal fractions with many zeros is quite impractical. To alleviate this problem scientists have introduced a decimal fraction of the unit watt. Usually they were recorded in degrees with a minus.

Today highlighted a dozen, but many of them are not used.

For example, the first two decimal fraction units watt: DVT (deciwatt equal to 10^-1 W) and SVT (centiwatt equal to 10^-2 W) is not recommended. But milliwatts (mW equal to 10^-3), microwatt (a microwatt is equal to 10^-6) and NW (NW is equal to 10^-9W) - one of the most used. And not only in payments but also in the manufacture of various measuring instruments.

For example, in medical devices such as electrocardiograph and electroencephalograph, the units are microwatt (µw).

In Addition to the above, there are five fractional units: picowatt (10^-12), femtowatt (10^-15), attowatt (10^-18), zeptowatt (10^-21) and yoctowatt (10^-24). However, they are used in rare cases and then only in the theoretical calculations.

Multiple units W

By Itself, the unit is relatively small. For example, to wash one kilogram of Laundry for one hour in an automatic washing machine class A++, you will need 150 watts of electricity. However, when you consider that the average simultaneously erased about 3.5 pounds of things, then consumes 525 watts. And this is only one wash, and how many of them going for a month or a year? Many as the number of consumed watts. To facilitate their entry on the basis of W are ten multiple units, recorded in degrees.

As with decimal fraction values, the first two of them (decawatt - 10¹ And hectowatt – 10²) is not accepted to be used, so that they exist only "de jure".

It is Worth noting that the recording cuts in multiples of units are often the first letters-capitalized. This is done in order not to confuse megawatts (MW – 10⁶) with microvilli (mW) and other similar values.

The Most used is the well known – kilowatts (kW). It is equal to one thousand watts (10³). Second - the aforementioned MW. This unit is most often used in the electricity sector. Rarely there are such values as gigawatts (GW – 10⁹) and TWh (TVT – 10¹²). For example, in one year, on average, humanity consumes about 1.9 TWh of electricity.

The Remaining four values – petavatthu (PVT - 10¹⁵), excavate (EVT - 10¹⁸), setiawati (Vecs - 10²¹) and yottawatt (IVT 10²⁴) – very rarely used, mostly to facilitate theoretical calculations. For example, according to one view, it is assumed that the total power radiated by the Sun energy equal 382,8 IVT.

Despite the many multiple and fractional units of watts, carry with them the math easy. It's easiest to translate everything into watts and then take action with degrees.

Another simple way to know the watts (the amount of using large or small, of related quantities) is to find in the Internet the online calculator. By the way, it is possible to translate W even in horsepower.

Watts and watt-hours

Having dealt with that in the unit of watts (as well as learning multiples and sub-multiples of its value and formula finding), should be given time to deal with such a close thing as watt-hours (W⋅h). Although the titles of the W and W⋅h are very similar, they represent slightly different concepts.

The Second unit is used to measure the energy produced over a certain time period (one hour).

To be more clear was the difference, one has to consider the work of ordinary kettle, with a capacity of 2200 watts. To prepare compote for the winter hostess almost continuously heated with the help of the water for one hour. During this time the instrument used 2200 W⋅h. If the woman took a weaker maker 1100 W, he would have boiled the same amount of liquid in two hours and would still used all the same 2200 watts⋅h.

All deliveries to consumers electricity is not measured in watts, but in watt-hours (usually in kilowatt-hours, also the ratio of one to thousands). To confirm this you can simply go to any brownie counter. Regardless of the country or the manufacturer, near the digits (showing the amount of used electricity) will be marked as "kilowatt hour" (kW⋅h). It can be also in English: kilowatt-hour (kW⋅h).

The power of any of its synthesizing power plant is measured in a conventional watts (kilowatts and megawatts).