How to convert volt amperes to watts? There is nothing easier. All you need to know is what “volt”, “ampere” and “watt” mean, plus a couple of formulas. They were known to everyone who graduated from school, but time goes on, something is forgotten. And when you suddenly need it, you can’t always remember. This article will help facilitate travel to the world of forgotten truths.
So welcome to the SI system.
Electricity Units
All three concepts: volts, amperes, watts are the main units that measure the phenomena in the world of electricity, that is, where the current "persons" are current and voltage. Like a chicken and an egg, one is impossible without the other, and no one knows what happened before.
Current strength and how it is measured
Andre Marie Ampère became for the science of electricity the same person as Newton for physics. The founder. People have known and studied physics and electricity since ancient times. But they became a science, in the modern sense of the word, when these scientists proved the empirical knowledge of the ancients with rigorous mathematics. If you rephrase Mayakovsky, we can say: "Ampere is a person and a unit." Because electric current is now measured in amperes.
If you pass a current of 1 ampere through two conductors, the distance between which is 1 meter, then they will be attracted to each other by a force of 2 * 10 -7 Newtons.
Who taught the world to measure stress
Alessandro Volta made a huge contribution to the study of electricity, so much so that he was named after a unit of force that makes electrons move. This voltage, or, in other words, the EMF is an electromotive force. The current increases if the voltage becomes larger, and decreases if it drops.
If you double the EMF, then, ceteris paribus, twice as much charge will pass through the conductor. What is meant by conditions?
Resistance without which there is no movement
The flow of electrons moves from minus to plus along a closed circuit. It has the property of resistance to the movement of current, which is the condition mentioned above. The definition of this property, reverse conductivity, was first given by Georg Ohm. Now the unit of resistance is Ohm. It denotes such a resistance through which a current of 1 amp flows, if a voltage of 1 volt is applied to it.
He introduced the formula I = U Ă· R, which also bears his name, into circulation. This is Ohm's law. The current strength is indicated by the letter "I". Voltage is written as "U". Resistance - "R". It can be seen from the formula that if U is increased without changing R, then I will also become larger to the same extent.
What can happen if you throw the resistance out of the circuit, the figure will show.
Hair on end is not the saddest consequence of such negligence. Another figure will show the role of resistance in natural phenomena. For example, the discharge of ball lightning.
What does the resistance have to do with it? If it were not, or it would be the same in all directions, the traces of the lightning discharge would be straight lines and spread to infinity.
James Watt enters the scene
The last character. He had nothing to do with the study of electricity. However, it is directly related to it. And all because the current, like any movement, produces some kind of work. To produce it, one must have power. Watt took measurements in this area. It was he who invented "horsepower."
But to measure electricity in "horses" is somehow illogical. They came up with another unit and named after James - watt.
The formula that relates power, voltage and current strength: P = U * I. The answer to the question of how to convert volt-amperes to watts is almost ready. And where are the volts and amperes?
Where did the volt-amperes go?
Here they just hid. If we substitute the units of measurement into the formula P = U * I for the symbols, we get Watt = Volt * Amp.
What turns out? Is a volt-ampere a watt? That is exactly the case. In the case of direct current, one expression is synonymous with another. Therefore, the question of how to convert volt-amperes to watts is easily solved.
For example, if you turn on the lighting in the car and measure the strength of the battery current, it is easy to calculate the power that is spent per unit of time. The voltage at the terminals is 12 volts, the ammeter showed 1.5, which means the result will be like this: 12 * 1.5 = 18 watts.
The simplest circuit diagram, where all the components of the calculations operate, is presented below.
Here, the light bulb plays the role of resistance, the battery plays the role of the current source, and voltage is invisibly present at the poles of the source. If you carefully look at the figure for the article, the role of all components will become clearer. The voltage “shoves” the current through the narrowing in the pipe, which is the resistance.
But power can be obtained in a different way. Since the current is equal to the voltage divided by the resistance, the formula can be rewritten as follows: P = U 2 Ă· R.
Other information can be extracted from the battery example. The question arose: how to convert watts to amperes in a 12 volt circuit? It is easy if you know the power of current consumers. For example, turn on the sidelights. Their power is known and equal to 24 watts. What current will flow through them? Divide 24 by 12 and get 2 amperes.
All methods of calculations and transformations are shown in the figure below.
Two triangles show the connections of all the "heroes" of the article. Voltage and current are present in both cases. Resistance and power are the third element.
If you need to get the value in the upper part of the triangle, you should multiply the values ​​in the lower part. For example, power will be equal to the product of voltage and current. And we easily translate volt-amperes (VA) into watts (W).
Is that all? Everything. But not quite
A forgetful, but thoughtful reader will reasonably ask: why each case of calculation is preceded by a mention of the battery. There is also alternating current. The conversion of volt-amperes to watts may be necessary in this case too. Are the above formulas suitable in such a situation?
They are almost always suitable, although coefficients reflecting its features are introduced into the formulas for a variable network. Sometimes they can be neglected. The results of calculations will almost always not differ too much from those given earlier. But why are they not quite the same as DC?
Because the AC power consists of 2 parts - active and reactive.
Active power is sometimes called useful. It is she who makes the incandescent light bulbs glow, heats the iron spiral and does all the useful work. The consumer pays for it on the counter.
Reactive power is used to create magnetic and electric fields in transformers, capacitors and other devices. It is usually small and is not taken into account in household calculations.
A glass of beer with foam clearly illustrates the electrical analogues of a foamy drink. Useful (active) power is the beer itself. Foam becomes synonymous with unnecessary, reactive power that cannot be used and must be blown away. Its a little.
Therefore, knowing how to convert watts to 12 volts amperes is also suitable for 220 volts. If not to be a pedant.
If you really need accuracy
The Internet is full of online calculators for all occasions. Including, you can convert watts into amperes for 12 volts. Need another calculation? You are welcome. Turn volt amperes into watts or vice versa.
And it is not at all necessary to know how to convert volt-amperes to watts yourself.