Amps vs. Watts vs. Volts?

cmeisenzahl

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Dec 16, 2002
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Can someone point me to an "electronics for dummies" type page, or explain this to me? I still after all these years don't understand the difference between these. My dad has tried to explain it to me several times with little success. :-(

Thanks in advance!
 

Nerd

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Lemme have the honour of taking up the challenge. Let's take electricity as water. Wire as garden hose.

Voltage is amount of pressure. So more voltage, more pressure, water shoot out of hose faster.

Ampers is amount of water. Bigger hose, more water can flow at one time.

To make it as unconfusing as possible, take your normal everyday garden hose: You pinch it, you get higher voltage, you change hose to bigger hose, more water can flow, but that doesn't = higher voltage because water may flow slower instead.

Watts = total amount of water flowing and at what speed = Volts x Amps.

Tell me which part do you not understand and I'll see if I can simplify it some more.
 

luxO

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"To make it as unconfusing as possible, take your normal everyday garden hose: You pinch it, you get higher voltage, you change hose to bigger hose, more water can flow, but that doesn't = higher voltage because water may flow slower instead."

No, pinching it adds resistance, voltage stays the same, current drops.
 

Empath

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The amount of worked performed by a circuit today was 100 watts.

It did it with 100 amps. It didn't take much force since it had so many amps. It only took 1 volt.

If there were only 50 amps, it would take twice as much force. It would take 2 volts.

If there were only 25 amps, it would take four volts.

............................

My men lifted 100 lbs today (watts). Their labor contract said they were only allowed to lift 1 pound each (amps). It took 100 men (1 volt each) to lift the 100 pounds.

The labor union renegotiated, and they can now lift 2 pounds each (amps). It now only takes 50 men (2 volts each) to lift the 100 pounds.

I'm trying to renegotiate for them to lift 4 pounds each (amps). That way, it will only take 25 men (4 volts each) to lift the 100 pounds.

........................

Watts (the work done) = Amps (the resources consumed) times Volts (the strength of the resource units)
 

McGizmo

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Let me throw this analogy at you:

Electrons do the work and the more that come through a gate and the speed at which they pass through, the more work (watts) can be done. The gate restricts how many electrons can pass through at the same time. The gate (wire) size dictates this number and think of this number as amps. Now the electrons can flow through the gate at different speeds (voltage) and the faster they go through, the more energy or power they impart (Watts).

Watts = Amps X Volts

It helps me to think of the electrons moving through the wire as I can see that amperage capacity is then a function of wire size (how many electrons can fit in the gate or tunnel cross section) and then I visualize the speed at which they are moving as the voltage or velocity.

To use this analogy further, consider a resistor or resistance as speed bumps
grin.gif
The electrons are slowed down at this point and a voltage drop occurrs. As the electrons hit the speed bumps and are slowed, energy is lost.

Another reason I like to think of voltage being the velocity of the electrons is that I can visualize electrons speeding through a wire and if they come to a gap in the wire, the faster they are moving, the farther I can see them successfully jumping across this gap (arc). The greater the voltage, the greater the arc.

The annoying static electricity is a result of a few, misbehaved electrons, going well in excess of the speed limit and doing Evil Kenevil stunts at our expense.
tongue.gif
 

Empath

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Chris,
Try to think in literal terms.

Watts: The amount of work to do.

Amperage: The resources (the number of electrons)you're working with.

Voltage: The power (the muscle of each electron)of each unit of your resources.
 

Jbirk

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Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Gray
White
 

INRETECH

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What is Electricity?
By Dave Barry

What in the world is electricity?

And where does it go after it leaves the toaster?

Here is a simple experiment that will teach you an important electrical lesson: On a cool, dry day, scuff your feet along a carpet, then reach your hand into a friend's mouth and touch one of his dental fillings. Did you notice how your friend twitched violently and cried out in pain? This teaches us that electricity can be a very powerful force, but we must never use it to hurt others unless we need to learn an important electrical lesson.

It also teaches us how an electrical circuit works. When you scuffed your feet, you picked up batches of "electrons," which are very small objects that carpet manufacturers weave into carpets so they will attract dirt. The electrons travel through your bloodstream and collect in your finger, where they form a spark that leaps to your friend's filling, then travels down to his feet and back into the carpet, thus completing the circuit.

Amazing Electronic Fact: If you scuffed your feet long enough without touching anything, you would build up so many electrons that your finger would explode! but this is nothing to worry about unless you have carpeting.

Although we modern persons tend to take our electric lights, radios, mixers, etc. for granted, hundreds of years ago people did not have any of these things, which is just as well because there was no place to plug them in. Then along came the first Electrical Pioneer, Benjamin Franklin, who flew a kite in a lightning storm and received a serious electrical shock. This proved that lightning was powered by the same force as carpets, but it also damaged Franklin's brain so severely that he started speaking only in incomprehensible maxims, such as "A penny saved is a penny earned." Eventually he had to be given a job running the post office.

After Franklin came a herd of Electrical Pioneers whose names have become part of our electrical terminology: Myron Volt, Mary Louise Amp, James Watt, Bob Transformer, etc. These pioneers conducted many important electrical experiments. For example, in 1780 Luigi Galvani discovered (this is the truth) that when he attached two different kinds of metal to the leg of a frog, an electrical current developed and the frog's leg kicked, even though it was no longer attached to the frog, which was dead anyway. Galvani's discovery led to enormous advances in the field of amphibian medicine. Today, skilled veterinary surgeons can take a frog that has been seriously injured or killed, implant pieces of metal in its muscles, and watch it hop back into the pond just like a normal frog, except for the fact that it sinks like a stone.

But the greatest Electrical Pioneer of them all was Thomas Edison, who was a brilliant inventor despite the fact that he had little formal education and lived in New Jersey. Edison's first major invention in 1877, was the phonograph, which could soon be found in thousands of American homes, where it basically sat until 1923, when the record was invented. But Edison's greatest achievement came in 1879, when he invented the electric company. Edison's design was a brilliant adaptation of the simple electrical circuit: The electric company sends electricity through a wire to a customer, then immediately gets the electricity back through another wire, then (this is the brilliant part) sends it right back to the customer again.

This means that an electric company can sell a customer the same batch of electricity thousands of times a day and never get caught, since very few customer take the time to examine their electricity closely. In fact the last year any new electricity was generated in the United States was 1937; the electric companies have been merely re-selling it ever since, which is why they have so much free time to apply for rate increases.

Today, thanks to men like Edison and Franklin, and frogs like Galvani's, we receive almost unlimited benefits from electricity. For example, in the past decade scientists developed the laser, an electronic appliance so powerful that it can vaporize a bulldozer 2,000 yards away, yet so precise that doctors can use it to perform delicate operations to the human eyeball, provided they remember to change the power setting from "Vaporize Bulldozer" to "Delicate."
 

0tr3b

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Originally posted by Empath:
The amount of worked performed by a circuit today was 100 watts.

It did it with 100 amps. It didn't take much force since it had so many amps. It only took 1 volt.

If there were only 50 amps, it would take twice as much force. It would take 2 volts.

If there were only 25 amps, it would take four volts.

............................

My men lifted 100 lbs today (watts). Their labor contract said they were only allowed to lift 1 pound each (amps). It took 100 men (1 volt each) to lift the 100 pounds.

The labor union renegotiated, and they can now lift 2 pounds each (amps). It now only takes 50 men (2 volts each) to lift the 100 pounds.

I'm trying to renegotiate for them to lift 4 pounds each (amps). That way, it will only take 25 men (4 volts each) to lift the 100 pounds.

........................

Watts (the work done) = Amps (the resources consumed) times Volts (the strength of the resource units)
<font size="2" face="Verdana, Arial">Just to clarify it a little bit, watt is a unit of power. The actual work done is measured in watt-hours or watt-seconds. High power makes quick work.

aa
 

Willmore

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Mar 5, 2002
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Hamilton, NJ
Short form:
V is voltage in, uhh, volts
I is current in Amperes
R is resistance in ohms
W is power in watts

Ohms law:
V=I*R
Power law:
W=V*I or W=I^2*R (using ohms law)

The rest is just different ways of arranging these equations.
 

dharmil007

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Thank You People for such a nice & wonderFul explanation.
i am on my way to understand this things.

Still i need a few clarifications, pls. can anyOne help me out.


1} In home sockets/plugs voltage is constant {240V in india}, so we just need to calculate & AmPs are given so we just need to calculate Power {Watts} with
formula P = V*I.
But sometimes this formula doesnt give accurate results.
I just saw my SMPS, which is 450W & has 230V & 5A.

Now according to the formula:
V*I = W
230*5 = 1150W

r8h84j.jpg


This doesnt get equal to the one mentioned on the SMPS.

y Is this so ??:thinking:


2} In Mobile phones or any device battery operated, how do we calculate electric consumption.
'coz it is measured in mAh {1000mAh = 1Ah}, but it has variable voltage.
& a lot others other things.

its just a lot of confusing.

Can someone pls explain in simple manner ?
 

HKJ

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Copenhagen, Denmark
Can someone pls explain in simple manner ?

I am afraid that there is no simple explanation.

With AC power the formula is not P=V*I, but need an added Power Factor (PF), this can also sometimes be called "cos phi".
I.e. the formula is P=V*I*PF
The PF is between 0 and 1.
For resistors the PF is 1, for most other stuff it is less than 1. Some equipment is marked with the PF (or cos phi).


When looking at ratings on the back of equipment the current is often specified to high. This value is used when you calculate the mains fuse, to avoid it blowing when you turn the equipment on.


Battery supplied equipment does vary in how they draw their power:
1) Some will draw a constant current, independent of voltage
2) Some will increase current draw when voltage drops, i.e. using nearly constant power.
3) Some will reduce current draw when voltage drops.
If you look in my flashlight reviews you will see a chart showing current and power draw, depending on voltage.
 

TedTheLed

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Feb 22, 2006
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I discovered something interesting the other day.

Electrons move very slowly through wire!

Its not the electrons doing the work so much as the magnetic field.

The electrons appear to move at or near the speed of light, say, when you flick a switch, and the light comes on immediately, because they are all packed in the wire 'shoulder to shoulder' and pushing the first electron in line causes the last electron in line to move..

but the speed of the electron is measured in feet per second! hard to believe, I know, counter-intuitive too, but check it out, Don. ;)
 

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