Watts, Amps, and Volts Explained

Discussion in 'General Electronics Discussion' started by Zarich12, Jun 13, 2016.

1. Zarich12

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Jun 7, 2016
I was wondering if there was anybody who could simply explain what watts, amps, and volt are? How do they relate and what do they mean. That has always been a big mystery to me. Thanks!

2. HellasTechn

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Apr 14, 2013
You have to digg in Ohms law to understad the above

3. HellasTechn

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Apr 14, 2013
Amps is the movement of electrons within a conductor, Volts are what cause the electrons to move (if closed circuit)

Watts is value of Amps * Volts and represents the power of a circuit

That is the simplest explanation i could ever give. Ofcource there is more to that.

Last edited by a moderator: Jun 13, 2016
4. HellasTechn

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Apr 14, 2013
a little more :

First things first. What is voltage ? voltage is the potential difference between two points. (Electric potential is a location-dependent quantity that expresses the amount of potential energy per unit of charge at a specified location.)

Assuming point A has a specific charge. Point B has no charge. The difference of charges between theese two points is what we call voltage.

Charged electrons have the tendancy to diacharge and when there is the phisycal means (eg wire across battery terminals) they do it and that movement is electrical current.

In other words voltage causes current.

Last edited by a moderator: Jun 13, 2016
5. HellasTechn

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Apr 14, 2013
See here.

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6. HellasTechn

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Apr 14, 2013
See here.
In water tank picture: the more pressure you have the more current you get given that the pipes diameter does not change.

Higher voltage will push more current through a resistor if the resistor value is kept the same.

Do i make sense ?

7. cjdelphi

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Oct 26, 2011
I thought about the water analogy and it does not quite fit

If you imagine water flowing as the voltage, think of the amount of bubbles being the current, more bubbles more current more voltage faster the water flow

8. Harald KappModeratorModerator

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Nov 17, 2011
This is not a good analogy.
• Think of the pressure in the pipe as the voltage - the power that drives the water through the pipe or electrons through the wire. If your tap is closed, there is still pressure, but no flow of water. As in e.g. a battery without a closed circuit attached there is voltage but no current. Voltage is measured in Volt (V).
• Think of the amount of water flowing through the pipe as the current (it is not incidentally that the same word is used ). Equivalently the electrical current is a measure of the number of electrons moving in the wire within a given time span. The more electrons, the higher the current. Current is measured in Ampere (A).
• The moving water can give off power, e.g. through a turbine. Similarly the moving electrons can give off power e.g. in a motor. The more electrons and the higher the pressure, the more power is available. Power is measured in Watt (W) and is calculated by P=I*V (Power=Current*Voltage) across an Ohmic load (resistor). When the load is not purely Ohmic, things get a bit more complicated.
• Think of the diameter of the pipe as the resistance. The smaller the diameter, the more pressure is required to force the same amount of water throughthe pipe. The higher the diameter, the less pressure is required. Equivalently the electrical resistance impedes the movement of the electrons within a wire. The higher the resistance, the higher the voltage required to force the same current. Resistance is measured in Ohm (Ω). This is expressed by Ohm's law: R=V/I (Resistance=Voltage/Current).
Take these analogies with a grain of salt. While in my opinion they can be a great help to get you started with electronics, they are by no means physically correct. Once you dig deeper into the filed, you need to become acquainted with the real physics behind electronics.

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9. HellasTechn

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Apr 14, 2013
No. water flow is current not voltage. what causes the water to flow "pressure" can be compared to voltage.

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10. BobK

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Jan 5, 2010
Current is movement of charge. Charge is measured in Coulombs. A movement 1 Coulomb of charge per second is 1 Amp, which is the measure of current.

Voltage is measured between two places. It tells you how much energy an charge gains or loses when moving from point A to point B. It is measured in Volts. A volt is the potential difference that would result in 1 Joule of energy being used to move 1 Coulomb of charge between the two points.

Power is energy consumed per second. Power is measured in Joules / second or Watts. So if 1 Coulomb of charge is moving through a potential difference of 1V every second, the power is 1 Watt. In other words, power is voltage times current.

Bob

11. Ratch

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Mar 10, 2013
Nice concise definitions. I would add that the circuit did not leak, and you did not get wet from the hydro-analogies. I would further add that current is charge flow, and current does not flow. Current exists or is present, but it does not flow. Also, Ohm's law pertains to the resistive linearity and not V = I R and all its variations. R = V/I is the definition of resistance, not Ohm's law.

Ratch

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12. Zarich12

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Jun 7, 2016
I once heard all these terms be likened to a water pipe with water flowing inside it. Can anyone tell me which parts are which?

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Jun 7, 2016
14. Ratch

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Mar 10, 2013
Electricity and water don't mix too well.

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15. Ratch

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Mar 10, 2013
Do hydraulic engineers study electrical circuits to understand hydraulics? If not, they why are you studying hydraulics to understand electrical circuits? Why confuse things with a mind melt of the two subjects. Each field of study is its own thing. What concept about circuits is it that you need to jump to another field to understand?

Ratch

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16. davennModerator

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Sep 5, 2009
I agree with Ratch
People have to give up on the bad water analogy. It only takes you a very limited way into the flow of charge and voltage potential, then it fails miserably.
It's better to learn the correct ways from the start so as not to spend time unlearning all the misunderstandings

Dave

17. Zarich12

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Jun 7, 2016
Yes, I uderstand that the water analogy is basic, but that's what I want is a basic answer.

18. Ratch

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Mar 10, 2013
It is basically wrong and confusing. For instance, voltage (joules/coulomb) is not equivalent to pressure (newtons/meter^2). What is there about electrical units that you do not understand?

Ratch