voltage & energy

[lboogy]

Hi everyone,

 

I'd be really appreciative if someone could clarify a few things for me.

 

1) If voltage is the potential difference, surely the 'difference' necessitates at least 2 different values, so there is something to differ. So, is the voltage the potential difference from one end of a circuit to the other?

 

2) Is the energy actually from the voltage? Or is it caused (transfered) when the voltage causes the charge to move through the circuit?

 

thanks

[Spyman]

1) Yes, the voltage is the potential difference between any two points in the circuit.

 

2) Voltage is the potential of the energy, electrical current is the quantity per time.

 

The amount of energy is the potential multiplied with the current.

 

Take two batteries with the same voltage but one is bigger than the other, which contains more energy ?

 

A larger battery contains more chemicals and can thus deliver higher current and/or sustain voltage longer time.

 

http://en.wikipedia.org/wiki/Electrical_energy

[lboogy]

thanks Spyman, I understand it now.

[insane_alien]

spyman, the energy is the charge multiplied by the voltage. voltage by current is power.

[Spyman]

spyman, the energy is the charge multiplied by the voltage. voltage by current is power.

 

The terms "electrical energy" and "electric power" are frequently used interchangeably. However, in physics, and electrical engineering, "energy" and "power" have different meanings. Power is energy per unit time.

http://en.wikipedia.org/wiki/Electrical_energy

 

The amount of energy is the potential multiplied with the current.

At the exact moment the measurement is taken, that amount of energy is transfered.

 

To get the total amount for a measured timespan you need to multiply with time also.

 

If a battery is charged for a longer time it will obviously also contain more energy...

(with the same voltage and current)

 

Was that what you meant ?

[timo]

1) If voltage is the potential difference, surely the 'difference' necessitates at least 2 different values, so there is something to differ. So, is the voltage the potential difference from one end of a circuit to the other?

It is a particle's potential energy divided by its charge - in other words a potential. Dividing the potential energy by charge removes the charge-dependence of the values so voltage is only dependent on the outer conditions and has the same value for all particles affected.

You do, in general, need two values to differ. Since only differences in values matter, it is physically irrelevant where you set voltage=0.

You simply set one point to zero, arbitrarily (there might be conventions in electrical engineering, though). In electrical circuits it usually means the difference from one end to the other of the part of the circuit that´s currently considered - which can either be a single part of the circuit like an LED or the whole circuit.

2) Is the energy actually from the voltage? Or is it caused (transfered) when the voltage causes the charge to move through the circuit?

Potential energy (voltage times the electric charge) can be transformed into kinetic energy resulting in movement. This is also true for electrical charged particles (e.g. electrons) in an electric field (electric potential). The kinetic energy of the moving particles can then go into other form of energy, e.g. warmth by friction in a wire (resistance), light in a lightbulb or mechanical energy in an electric motor.

[imp]

Hi everyone,

 

I'd be really appreciative if someone could clarify a few things for me.

 

1) If voltage is the potential difference, surely the 'difference' necessitates at least 2 different values, so there is something to differ. So, is the voltage the potential difference from one end of a circuit to the other?

 

2) Is the energy actually from the voltage? Or is it caused (transfered) when the voltage causes the charge to move through the circuit?

 

thanks

 

The trick I use for understanding voltage is that voltage can exist only between two points; it does not "flow", and it does not show up as "there's 20 volts here". Here"? Where? Has to be between two points. Remembering that has always helped me. imp