Difference between volts and amps ???

Maybe I should use a hose. Or maybe Kirkoff's current law. I probably spelled that wrong. Benn out of college 25 years.

Watts enter the picture as usage, i.e. how much you can draw from a source (water tower or battery) before it needs refilled.

The electric utility measures in kilowatt hours which is 1000 watts used over a one hour period.
They don't care whether you use it with 10 100 watt lightbulbs over one hour, or 10 50 watt lightbulbs over two hours, just that you have used it. You could even use a 1000 watt iron to iron your jeans for one hour in the dark--all use 1 kilowatt in the examples.

While we don't really think about needing to replace watts into our tractor or auto battery, in essence we should. The more we pull from it, the more gasoline or diesel our engine burns to power the alternator or generator to replace it.

A number of years ago when there was a fuel crunch, the US Postal Service had their carriers drive without lights on. Usually they ran with them on for safety. Can you imagine how much fuel was saved by running 200,000 vehicles 6 days a week without that extra little drag of the alternator? While it doesn't seem like it would be much, I'll bet it did add up. Same with todays autos running with lights on all of the time. Think of the savings if all went dark during daylight hours.

On your first example 110 volts X 15 amps would equal 206.25 drops of water (watts) out of each plug (sprinkler) if used equally.

Second example: 110 volts X 20 amps would equal 220 watts out of each plug if used equally.

The second circuit will carry a tolal of 2200 Watts (drops of water) while the first will only carry 1650 drops of water (watts).

Clear as mud, right??

Volts are similar to water pressure, i.e. more push. The higher the water tower or the higher the pressure a pump is putting out the more push. Same with higher voltages, more forceful. Fire hose vs. garden hose, more forceful.

Amps are compared to the flow of the water. Think of your ampmeter as being similar to the water meter in a water system.

A 12 volt system has more push, so we use smaller lines than a 6 volt system to deliver the same product. Kind of like a 1" water line using high pressure vs. a 4" water line using very low pressure. They can both deliver the same about of product, one more cost effectively due to smaller lines. Think high voltage lines vs. farmstead lines.

Then end product is watts or a bucket full of water. Neither of which we are really concerned about unless we are thinking of replacing what is in the battery or water tower. Then we have to consider lighting, starting, AC blower and clutch usage, etc. Then we have to consider how big of an alternator we need, or how big of a pump if considering it like water.

Volts multiplied by amps gives usage, i.e. watts.
Watts divided by volts gives how many amps were used.
Watts divided by amps shows how much push there was, i.e. volts.

The best analogy I've ever heard is the old garden hose comparison.

The hose is the circuit, the water within that hose is the current and the water pressure at the faucet is the voltage.

Allan

for simple resistance circuits. Even DC gets more complicated when you have motor armatures that are or are not turning, but we are fortunate that we don't have to contend with AC on our old tractor circuitry.

Amps = Electrical "flow".

The two are related, in that a doubling of the voltage will cause double the current to flow, provided that the resistance doesn't change. That's why it's so important to have good heavy conductors, good grounds and clean connections in the starting circuits of those old 6 volt tractors. You can't control the voltage available, and you can't change the resistance of the starter, so the only thing you do have control over is the resistance in other parts of the circuit. With large conductors (battery cables) and clean connections, the maximum amount of current will be available at the starter.

To take that one step further---watts are like the gallons, i.e. the total amount of flow that is caught in a bucket or used.

If anyone is interested in solar--if you have 10 100 watt light bulbs burning for one hour you have consumed 1000 watts or one kilowatt hour.

Using the formula volts X amps = watts (times length of time for watt hours), you can arrive at how many amps you need whether you are using 110 volts or 12 volts. The wattage is what you figure from. Of course you also have to factor in some energy loss as not much of anything is 100% efficient.

For solar needs, convert the amps to watts, figure how long each item will be turned on, then figure total watt hour requirement. From there you figure how many solar panels you will need to catch the watts over the length of day you have.