Voltage, Current, Coulombs... ?

Question

I'm in Grade 9 Science and all of this electricity stuff is getting on my nerves. I'm particularily confused with voltage. "The potential difference between two points on a curcuit in relation to blah blah blah..."; no, that crap just won't cut it. I don't know what the hell it means. My teacher just shows us the calculations for stuff and doesn't thoroughly explain anything. This is my worst unit yet. Can someone explain to me what these terms mean in a way that I can understand? I want to know a bit about what I'm working with here.

Also, how the heck do batteries work? My teacher goes on about these "cells" with a short line (-) and a long line (+) or something like that... but I have no idea what the heck she's talking about. Does she think we've learned about batteries already or something?

One more thing: Our teacher sais electrons flow out from the "negative terminal" on a battery. What I want to know is: WHY? What goes on inside a battery anyways?

Answer 1

You can use an analogy to water:
Voltage is like pressure.
Current is like the flow rate (amount per second)
Charge (measured in coulombs) is like an amount of water in a jar.

You can have a tiny, fast jet of water - high pressure (voltage), low flow rate (current).

You can have a wide, deep ditch full of slow-moving water - low pressure (voltage), large flow rate (current).

"Negative" is just a convention. People had to agree on one word or another, and that was it. By convention, negative is where the electrons come from. In a battery, energy from chemical reactions releases electrons, and drives them at a voltage set by the energy of the reaction. One reaction chamber is a "cell." If you need more voltage, like in a car battery, you can use multiple cells strung together in series. A battery acts like a pump - if you need to raise water very high, you might need multiple pumps in series to overcome the pressure due to gravity.

The schematic symbol for a battery looks like two plates facing each other. That's actually what the first batteries looked like, two metal plates separated by a fluid that conducts a current. You can't see that in the batteries you buy today, so the symbol doesn't make as much sense any more.

Answer 2

Okay, I'm in grade 9 science too - takes deep breath- Voltage is the same thing as potential difference, it's the thing that moves electrons in a circuit. Current is measured in amperes and is the number of electrons moving through a circuit. Coluombs are the unit of measure for charge. Curent is the movement of charge.
Batteries are electrical cells which have 2 terminals. Negative and positive. In a circuit -a closed path that connects electrial components(batteries, electrical appliances, swtiches,etc) , the electrons flow out from the negative terminal, around the circuit, and come back through the positive terminal. In the batttery, a substance called electrolyte 'pushes' the electrons back to the negative terminal and the process starts again.

Think of it like a waterfall with a water wheel. Water falls down easily (due to gravity) and turns the water wheel. Then it rests at the bottom. There, a pump has to pump the water back up to the top of the waterfall, and the process starts again. Same concept in a circuit. Electrons, the water, flow out easily from the negative terminal, the top of the waterfall, and through the electrical appliances (the water wheel) and back to the positive terminal ( bottom of waterfall). There the battery (the pump) has to force the water back up to the negative terminal (top of waterfall)

Get what I mean?

Answer 3

You basically want a semesters worth of knowledge crammed into a couple sentences.

Do you like analogies?
Imagine a full tub of water placed on a tower. A hose is connected to the tub through a faucet.

The tub is the power supply or battery. The faucet is the switch. The hose is the conductor. And the water is the current (electron flow).

With the faucet off, there is pressure on it (due to gravity, in this case). That pressure is like voltage (more water, more pressure). If you open the faucet (turn on the switch), water (or current) flows.

The larger diameter the hose, the less resistance to flow, and the more water flows (more current).

Current is how many electrons pass a single point in a second.

Voltage is what is pushing the current. Of course just like the water, the mass of the water in the tub is pushing it, but the gravity is also pulling it. For current to flow, it has to have someplace to go (or pulling it).

This of course is the tip of the iceberg. Hope it helps a little.

Answer 4

Voltage is the FORCE of electricity.
Current is the AMOUNT of electricity per second.
Coulombs is AMOUNT of electricity.

Inside a battery, there is a chemical reaction that pushes electricity toward the terminals. The electrons have negative force, and they get pushed toward the negative terminal. Chemical ions have positive force, and they get pushed toward the positive terminal. (Ions can be positive or negative, the ones inside batteries are positive.)

When a bunch of electrons gather at the negative terminal, and have nowhere to go, they push back and stop the chemical reaction. When you connect a wire between the terminals, the electrons can go through the wire and join the positive ions at the positive terminal. The electrons and the ions get together and cancel out -- they make a neutral molecule that has no electric force. That leaves room for the chemical reaction to make more electrons and ions.

Answer 5

A little to help your perhaps ......

An analogy to simple hydraulics is sometimes used to introduce basic electricity.

Voltage is analogous to pressure.

When there is a pressure difference across a hydraulic system, a current of water flows through it.

When there is a voltage difference across an electrical circuit, a current of electrons flows through it.

Voltage is named after the Italian physicist Volta. The unit being the volt (with a lower case v), but abbreviated to the upper case V.

Current is named after the French physicist Ampere. The unit is the ampere (with a lower case a), but abbreviated to the upper case A.

The value of current, for a given applied voltage, depends upon the resistance to flow, called, would you believe, resistance.
Resistance is named after the German physicist Ohm. The unit is the ohm (with a lower case o) but abbreviated to the upper case Greek letter Omega - which I can't type here.

These three units are related through Ohms' Law, which states that the current through a resistance is equal to the value of the applied voltage divided by the value of the resistance - and its two corollaries.

I would have though that while I have been typing this that there there will be other answers keen to display the simple formulaes.

The Coulomb is the unit of charge, named after the French engineer Coulomb. It is described as the "quantity" of electricity conveyed in one second by a current of one ampere.
It is also described as 6.24 x 10^18 electrons per second.



You will find much useful basic information in the net, but heres a few links to start looking at (I haven't checked them out fo a while) http://www.davidbridgen.com/links.htm

Answer 6

Let me first begin with Current. In order to explain current I will have to explain an Atom and its composition. Basically an atom is what matter is made of. So yes, you and me and everything is composed of something very small that we can not see without special instruments call Atoms. The atom is basically composed of Protons (positive charges +), neutron (neutral charges) and electrons (negative charges -). The movement of these electrons is call electricity or current if you and me want to use the correct terms. So current is the flow of electrons. If we use a machine to measure it scientist decided to call the unit of current AMPERE (name after a french scientist that worked with current). I know probably all this still complex so let me use an analogy(somethign similar to explain to you what is going on). Let me use water. You probably have or have use a hose before right??? Well the hose with water inside will throw out water. The flow of this water thru the hose until the water is out of the hose is like the electrons moving from one point to another. This will be electricity or current. Yes, current of water move in a similar way to a current of electrons. Now let me explain Voltage. Again I'll use the water hose as and example. If you use diferrent hose sizes you will see that water flow will vary. Also if you press with your hand the hose at some point you will see that the water out of the hose will vary. This is because you are causing a variation of "preassure" in the hose. Well the preassure needed for the flow of water is call WATER PREASSURE". In a electrical Circuit (like the water hose) is called Voltage. Finally Coulombs is just a unit of meassure of electric charge. Let me use the clock to explain. What unit you use for time? Seconds??? Minutes??? hours??? all those are units of time. Well the official unit scientist use for electric charge is the Coulomb.

About the batteries there is a long explanation on how they work but there are somethings that are still not clear to scientist how they work. For example we know batteries accumulates or saves energy in the form of current. But we don't know yet how they loss that energy even without using them. We have a hipothesis (something we believe happens) but I'm not going into that since I don't want to confuse you. About the flow of electrons from the negative terminal of the battery that your professor mention is just a something that scientist don't know for real but agree to accept like that for purposes of standarization(in other words every body doing things in the same way).

The last thing have to say to you about all this is...give the opportunity to the professor to teach you eventhough you may think you are not going to be able to learn you will eventually do. Its like anything new in life, it take some time for us to adapt to the new words but eventually you will undestand very well everything specially doing what you are doing, getting help and more info. I hope this help you. Take care!

Answer 7

Hey, so many questions in one question.

I know it can be confusing, but here is a simple analogy with water that always made it easy for me to understand.

If you imagine a pipe with water being similar to a wire with electricity going through it just like water goes through the pipe.

Then: the pressue of the water in the pipe is like voltage. Pipe, or water hose with lots of pressure (meaning it can shoot high in the air if you point it up, kind of like firetruck), it's the same as a wire with high voltage.

Now, imagine a huge pipe versus a small hose. Much more volume of water goes through a thick pipe than a small hose. In a wire, that would be called a current. You can transfer much more water through a big pipe that through a small hose. Same thing with wires, much more current can go through thick wires, than tiny ones.

Another cool thing that comes out of all of this is understanding of where the danger from electricity comes in. What kills a person is current, not voltage. For example, a person might be shot with 100,000 volts, but 0.000000001 amp, and it will not be deadly or even noticable.

While a person might be fried and killed instantly with let's say 12 volts (car's battery) and 50 ampers.

Same as with water, a strong slow moving mass of water will carry a car away and knock the person off his feet, while a strong, fast beam of water will not do as much damage, though it's much faster.

Hope this helps.

Answer 8

connect a fire and and ice with a wire...will the ice melt?
yes...the heat is conducted...
the fire has higher temperature...and ice has a lower..

the + terminal of batter has higher potential..or more charge..
and -ve has no charge...
electrons taken to be negative in charge are more in -ve terminal..obvious .right?
so they flow from higher concntration to lower...

this is called electricity...as it flows it passes through all that comes in its path...in heat the potential is represented by temperature...
and heat flowing is similar to current..
to understand about electrons etc...you ll hav to learn chemistry...the ions provide electrons..and its really complicated..wait till 11th or 12th ..so you ll learn things..

Answer 9

Check out these webpages. First is very simple second is more detailed and complicated.

http://www.rayovac.com/wizard/battery_howwork.htm

http://www.howstuffworks.com/battery.htm