Many questions about how electricity works.

[srams]

I'm hoping to get some answers here from those who have knowledge of just how exactly electricity works.

Watts, Joules, Ohms, Volts; etc... I know a little about them but could always use more answers.

How does one not electricute him/her self when welding on the surface they are standing on or under water?! Don't say "they're grounded" or what ever I don't know what that means! Can I hold on to an object that I am welding?

More to come as I think of them. Thanks for any help!

[Oramac]

DO NOT HOLD THE THING YOU'RE WELDING!!!!  You will electrocute yourself. 

In welding (and pretty much any other electrical application for that matter) electricity always travels in a circle, or circuit.  The term "ground" is just a fancy way of saying "completes the circuit".   Electricity will always take the easiest route to complete its circuit.  In welding, you simply control what that route is.  You connect your ground wire (or "completion wire") to the thing you're welding, and the thing you hold (has different names, I'll call it the Stick) is the other end of the circuit.   So electricity flows from the welding machine through the stick, into and through the metal being welded, through the ground wire, and back into the welding machine.  The circuit is complete.  The heat generated by the electricity flowing into the metal is what melts it to form the weld. 

This isn't strictly accurate as far as physics is concerned, but it's helps me remember. Ohms is a measure of resistance.  Think of a wire like a hose.  Water flows through the hose, but if you restrict it, there's resistance.  Voltage is like pressure.  You pump water through the hose.  High voltage is a really powerful pump.  Amperage is flow.  So if you have water going really fast through the hose, it's flow is high.  Amps and Ohms are opposites.  High amperage means low Ohms, and vice-versa. 

Also remember: voltage won't kill you.  Amps will.  Lightning is extremely high voltage, but low amperage, and you can survive it.  But 1 amp, just ONE amp, is enough to kill you. 

[Darth Kitsune]

http://en.wikipedia.org/wiki/Electricity
http://www.leonics.com/support/article2_2j/articles2_2j_en.php

[srams]

DO NOT HOLD THE THING YOU'RE WELDING!!!!  You will electrocute yourself. 

In welding (and pretty much any other electrical application for that matter) electricity always travels in a circle, or circuit.  The term "ground" is just a fancy way of saying "completes the circuit".   Electricity will always take the easiest route to complete its circuit.  In welding, you simply control what that route is.  You connect your ground wire (or "completion wire") to the thing you're welding, and the thing you hold (has different names, I'll call it the Stick) is the other end of the circuit.   So electricity flows from the welding machine through the stick, into and through the metal being welded, through the ground wire, and back into the welding machine.  The circuit is complete.  The heat generated by the electricity flowing into the metal is what melts it to form the weld. 

This isn't strictly accurate as far as physics is concerned, but it's helps me remember. Ohms is a measure of resistance.  Think of a wire like a hose.  Water flows through the hose, but if you restrict it, there's resistance.  Voltage is like pressure.  You pump water through the hose.  High voltage is a really powerful pump.  Amperage is flow.  So if you have water going really fast through the hose, it's flow is high.  Amps and Ohms are opposites.  High amperage means low Ohms, and vice-versa. 

Also remember: voltage won't kill you.  Amps will.  Lightning is extremely high voltage, but low amperage, and you can survive it.  But 1 amp, just ONE amp, is enough to kill you. 

What if I'm holding pieces on the grounded table?

The volts and amps are what I'm really confused about. I was told voltage is like the electricity resivoir. If I have a 10.8v (12v) drill it has three 3.6v cells, 18v has five 3.6v cells etc. If that means your power reserve is higher than why are the rpm's and torque higher in the 18v drill? Wouldn't that have to do with amps not volts?

How can one amp kill? How can 50000 volts not kill? How is lightning less than one amp but my saw is 8 amps?

[WookieeGunner]

Picture an item on a desk.  If you pick it up, it will have postive potential energy compared to what it had on the desk.  If you knock it on the floor, it will have negative potential energy compared to what it had on the desk.  Voltage is the same way.  You measure voltage from a common reference.  The biggest common reference is the Earth itself, or in other words, the ground.  This is exactly where the term comes from as a copper spike in the ground is a commone way to give a building a single voltage reference.

Now, if you are holding that object above the desk and you let go, the object will travel from your hand to the desk (assuming nothing is in the way).  Voltage will also do this.  When we say someone or something is grounded we mean that there is nothing in the way for the electricity to go through them or it to the ground as that is its favorite place to be.  Since electricity is lazy and always takes the easy way out, sometimes going through the person is easier than go the way it is supposed to (for example through the welding machine and back down the power cord to the outlet.  This is what causes people to get electrocuted.

To answer your drill question you have to understand Ohm's law.  Ohm's law states that current is equal to voltage divided by resistance.  Voltage is easier for us to measure so tends to be used more often than current.  So when you have two items (say drills) that have roughly the same resistance, by raising the voltage you also raise the current.

Voltage is like the water behind a dam.  There maybe a bunch of it, but if it is only trickling through a one inch spout on you then it's not going to hurt you much.  On the other hand, if you are standing in front of a fire hose attached to a pump truck, there may be a lot less water (voltage) but the flow (current) through the firehose is going to hurt when it hits you.

[Darth Abaddon]

Just to clear up a little.

The ground wire/antenna/whatever is to direct the current into the ground so that you don't kill yourself.

The amount of current that will kill you is a lot lower than 1A at between .1A and .2A.

Wookiee has it absolutely right with the firehose/dam reference. So in going on what Wookiee said, You can take 10,000 volts and .001A and be fine, whereas if you were to get whacked with 1,000 volts and take .2A, you will die.

Ohms are a measure of resistance. Resistors are there to resist flow and keep the device from blowing itself out. To find the resistance value of a resistor, they are color coded to get the equation.

Black-0
Brown-1
Red-2
Orange-3
Yellow-4
Green-5
Blue-6
Violet-7
Gray-8
White-9

Gold-+/-5%
Silver-+/-10%

So say you have a resistor color coded green, violet, orange, gold. Depending on how many colors will determine the numbers in the equation, up to 3 figures. So for the example

5(green)7(violet)X10^3(orange) with a +/-5% of tolerance(gold)

so 57x10^3 +/-5%

57000 ohms +/-5%

57000X.05=2850+/-

between 54150(high)-59850(low) ohms is what that resistor can handle

Dunno that you work with resistors but that's where ohms come in at so I hope that helps.

[srams]

I might just have to start PMing people because I still dont really get it..

I guess one good place to start is WHY do Amps kill but Volts dont?

[Darth Kitsune]

Just to say, even if you don't get it, you COULD just follow with safety routines anyway so you don't injure yourself.

[srams]

Yeah, of course, but I want to know how every thing works the way it does and why. I can read the internet all day but its nice to be able to ask my questions where people can answer them.

[Darth Abaddon]

I might just have to start PMing people because I still dont really get it..

I guess one good place to start is WHY do Amps kill but Volts dont?

I have to say I'm not entirely sure but I have an electronics lab tomorrow morning. I'll ask my teacher.

[Oramac]

I guess one good place to start is WHY do Amps kill but Volts dont?

Think of the Water Behind A Dam example again.  If water is trickling through slowly (voltage) it's basically harmless.  You could dance in it and be fine.  But if the dam breaks and the water all flows through at the same time (amperage) you'll drown.  Same thing with electricity.

[JEStucker]

I spent ten years as an electrician... after consulting the pile of books in my basement, the best answer I can give is...

[srams]

Hahaha! That guys in like every other show I watch. Although I still can't remember his name

[Darth Abaddon]

Quoted from my DC teacher. Voltage is the potential energy flowing through while current is the actual electrons.