What is voltage drop?

[scilearner]

Is voltage the potential energy difference between source A and B in a circuit? If so in absense of resistance and the presence of a 3V battery does point A have 3V to begin with and at point B there is 0 volts. Is all potential energy converted to kinetic energy when moving from A to B? A is origin and B is the terminal end of the circuit by the way. Is that voltage drop?

 

If what I have said is not correct and voltage doesn't drop like this does a circuit with no resistor and negligble resistance from the wires have 3V at point A and also 3V at point B?

 

Let's say that I have a circuit like this (made it linear for ease)

 

3V battery--point A----------------1ohm resistor-------------pointB

 

What is the voltage of the resistor? It is 3 right. Does that when current passes through the resistor it loses 3V. If it loses all the voltage how does it move to point B?

 

Thanks

 

Edit: I think I'm assuming when they say voltage drops across the 1 ohm resistor is 3, the 1 ohm resistor uses all 3V. When they say voltage drop in this case are they actually referring to voltage drop from A to B. The actual amount of energy lost due to the resistor is not really 3V. It is something less. The voltage drop across the whole thing is 3 V. Is that right?

Edited November 22, 2009 by scilearner

[tvp45]

Voltage is the potential energy per unit charge. There is always a potential difference causing current, even when it is very tiny. Let's say you have 3.000 V at point A. This means relative to point B. The end of the resistor nearest point A might have somethin like 2.9989 V, the small difference being what it takes to make the current in the wire. Likewise, at the end of the resistor nearest point B, you might have 0.0008 V, again the small potential difference being needed to have current in the wire.

 

We normally just ignore the small potential differences across the wires.