# Can someone please explain Voltage?

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#### nabilesmail

##### Full Member
10+ Year Member
Can someone please explain voltage especially in a circuit? I don't understand voltage drops (what does that mean) all I know is that charges move from high potential to low potential, and that high potential=a lot of positive charge there (so electrons technically move to high potential). I know the formulas and all, but have always struggled to understand this part (relevent to circuits).
also is potential, potential difference, all the same?
Thanks!

#### sc4s2cg

##### Full Member
10+ Year Member
Voltage is just a potential difference.

The way I think about it: there are electrons at the negative side of AA battery, and there are no electrons on the positive side. The electrons want to get from the negative to the positive, but they are blocked from doing so in the battery itself. When you connect the wires, the electrons do everything possible to get to that positive side, even if that means they will slow down a bit (resistors).

Basically, voltage is how "bad" the electrons want to get to the other side. But, of course, this is just how I keep stuff straight in my head.

#### nabilesmail

##### Full Member
10+ Year Member
so what does voltage drop mean? Thanks by the way!

#### circulus vitios

##### Full Member
10+ Year Member
15+ Year Member
so what does voltage drop mean? Thanks by the way!

Voltage drop means the decrease in voltage across a circuit element, like a resistor.

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#### sc4s2cg

##### Full Member
10+ Year Member
so what does voltage drop mean? Thanks by the way!
So, to continue the analogy..

The electrons are wanting to get from the negative to the positive, and their desire is quantized by 6Volts. They want to get there so bad, they are willing to expend 6 Volts (I want to get to my friend's house so bad I am willing to burn 6 gallons of gas. Very bad analogy, but hopefully it helps). Once the electrons reach the positive end, we say they used 6Volts, that is the circuit had a 6Volt voltage drop. So that's what that is. To go a bit further:

So the electrons are running along, and the electron at the very front finds a resistor. It tries to get through, but the resistor is not nice and straight and perfect like our ideal wire is. It is all twisty and stuff. This causes the electron to slow down, cause a traffic jam, and make the electrons behind it slow down as well. In other words, the current slows down. But what is the electron to do? It still really wants to get to the positive end, but now it is rethinking it's chances. The resistor is measured to be 3Ohms and the current is 1 Ohm. This means the Voltage on the resistor is only 3Volts. So now the electrons have less desire to get the positive side. We say that this resistor had a voltage drop. Why did this occur? Because the potential energy of the electrons (the voltage) has been converted to other forms of energy in the resistor, mainly heat.

This is a great website for circuits. Here is the link for serial circuits, and here is one for parallel circuits. At the top you can go through other lessons, but these two links do explain voltage and voltage drops. #### dynamicalan

##### Full Member
7+ Year Member
If you want to measure voltage you put up a meter to an electronic circuit. Let's use a real simple dc circuit in series. If you put both leads on the same side of the resister then the voltage will read 0 volts because no current flows through the meter and the arm doesn't move but if you put it across a resistor then it will show the difference across that resistor. So, if you look at the circuit lets say connected to a 12 volt battery connected to four 1 K Ohm resistors then when current is flowing through the circuit each resistor drops 3 volts. What happens when you disconnect the battery? The voltage drops go away and there's no potential. However, if you measure across an open, not on one side of the open, you measure the difference in potential the battery has. In order to measure voltage current has to flow. The meter acts as a load. It offers a low resistance to current flow and an external branch for that current to flow through. It takes lot of coulombs (Static Electricity) to measure any voltage. Thanks for the link. I would like to review it.

My experience in understanding voltage has been that the practice of Kirchhoff's law makes understanding voltage, current and power easier. If you draw some series and parallel circuits and use these laws for voltage and current then it will make sense. I'm talking about a simple circuit such as three branches for a basic parallel circuit and and a few resistors for a series circuit. You may notice that all three paths of current flow into one path when they join together all three are added but the resistance is not. there's a formula to figure this out. it decreases for each branch. If you start with a 4 ohm resistor and a 12 volt battery the you have 3 amps for the first branch. If you duplicate that branch you get another 3 amps equalling 6 amps so the total resistance goes down to 2 ohms which is half. 4/2=2. The formula is 1/r1 + 1/r2 + 1/r3 ...1/n. This above formula is given in the next section of the above link. I suppose I should've just said: By tracing a few circuits can really help a lot. The only reason I added this to the obvious is because at one time I only memorized the actual Kirchhoff's law and it takes practice.

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