How do you picture yourself current and voltage in a circuit?
I am having a hard time with these abstract notions.
I've tried doing an analogy with water pressure but now I have found out current and voltage can both be positive or negative!
So I need some help
Answer:
The water pressure as voltage and the water itself as current is a reasonable analogy, even if you're talking about AC which changes directions.
But even more useful is to understand the actual phenomena. You know that atoms are a heavy positively-charged nucleus surrounded by a cloud of light-weight negatively-charged electrons. And I'm sure you know that opposites, attract, that a positive charge is attracted to a negative charge, and visa-versa. What a positive voltage source does is pulls electrons off of atoms. Once this happens, the atom has a net positive charge because now there are more positive charges in the nucleus that negative charges in the electron cloud. So now that atom attracts an electron from a neighboring atom to rebalance itself. Now the neighboring atom has a shortage of electrons and it now attracts an electron from an atom even further away from the original positive voltage source. And this process just continues. There is a voltage source that is able to suck electrons in at one end of a circuit and pump them back out into the other end of the circuit. It can do so via a chemical reaction like in a battery, or it can do it via induction, like in a generator. How strongly it pulls/pushes (pumps) the electrons is measured by voltage (pressure), and the flow of electrons, in couloumbs per second, is current. That's not too hard to understand, is it?
Think of a current as a stream and voltage as a waterfall.
Voltage is simply electric potential, meaning that negative wants to go towards positive. So in a sense, this is like gravity. When an object is higher (farther away from the center of the earth), it wants to fall. If there is something blocking it from falling, it will not fall. If there is nothing blocking it, it will fall.
Same with electricity. When there is nothing in the way of current moving, then it will move. However if you put in *resistance,* the current may not move, or it may move much slower. The amount of voltage is similar to the height of the waterfall...the higher the water is, the more 'potential' it has.
You were right in saying that current can be done by both positive and negative charges, but if you're in a physics class right now, you're almost exclusively talking about electrons moving. Take a copper wire for example. The way atoms of metals work to make a solid is by getting very close to each other and allowing electrons to flow freely from one atom to the next. This may be an oversimplification, but you see my point. So in some copper wire, you could have an electron on one end of the wire and have it pass all the way through with no problems if you give it enough energy or time. But there's no way a proton can move through the copper wire, mainly because it's stuck to other protons and neutrons. So to continue the stream/waterfall analogy, a proton would be a boulder.
I say the voltage is how wide the river is, current how fast the water is flowing. But beware analogies never tell the whole story.
Current is analogous to the volume of water flowing through a pipe. Voltage is analogous to the pressure of the water. A negative value means "in the other direction".
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I've tried doing an analogy with water pressure but now I have found out current and voltage can both be positive or negative!
So I need some help
Answer:
The water pressure as voltage and the water itself as current is a reasonable analogy, even if you're talking about AC which changes directions.
But even more useful is to understand the actual phenomena. You know that atoms are a heavy positively-charged nucleus surrounded by a cloud of light-weight negatively-charged electrons. And I'm sure you know that opposites, attract, that a positive charge is attracted to a negative charge, and visa-versa. What a positive voltage source does is pulls electrons off of atoms. Once this happens, the atom has a net positive charge because now there are more positive charges in the nucleus that negative charges in the electron cloud. So now that atom attracts an electron from a neighboring atom to rebalance itself. Now the neighboring atom has a shortage of electrons and it now attracts an electron from an atom even further away from the original positive voltage source. And this process just continues. There is a voltage source that is able to suck electrons in at one end of a circuit and pump them back out into the other end of the circuit. It can do so via a chemical reaction like in a battery, or it can do it via induction, like in a generator. How strongly it pulls/pushes (pumps) the electrons is measured by voltage (pressure), and the flow of electrons, in couloumbs per second, is current. That's not too hard to understand, is it?
Think of a current as a stream and voltage as a waterfall.
Voltage is simply electric potential, meaning that negative wants to go towards positive. So in a sense, this is like gravity. When an object is higher (farther away from the center of the earth), it wants to fall. If there is something blocking it from falling, it will not fall. If there is nothing blocking it, it will fall.
Same with electricity. When there is nothing in the way of current moving, then it will move. However if you put in *resistance,* the current may not move, or it may move much slower. The amount of voltage is similar to the height of the waterfall...the higher the water is, the more 'potential' it has.
You were right in saying that current can be done by both positive and negative charges, but if you're in a physics class right now, you're almost exclusively talking about electrons moving. Take a copper wire for example. The way atoms of metals work to make a solid is by getting very close to each other and allowing electrons to flow freely from one atom to the next. This may be an oversimplification, but you see my point. So in some copper wire, you could have an electron on one end of the wire and have it pass all the way through with no problems if you give it enough energy or time. But there's no way a proton can move through the copper wire, mainly because it's stuck to other protons and neutrons. So to continue the stream/waterfall analogy, a proton would be a boulder.
I say the voltage is how wide the river is, current how fast the water is flowing. But beware analogies never tell the whole story.
Current is analogous to the volume of water flowing through a pipe. Voltage is analogous to the pressure of the water. A negative value means "in the other direction".
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