Energy conversion?

Status
Not open for further replies.
B

bthielen

Guest
To my knowledge we are not able to create energy, only transform it from one form to another. For example, we can convert electrical energy into heat energy. At least I am not aware of anyone that has perfected a perpetual motion machine yet.

With this assumption, I have been curious about how it is that when we send electric current through a heat element converting energy into heat, what energy is actually being converted? If it is the electric current, then how is it that the return current on the grounded conductor is the same as the supply current? If we are in fact converting some of the electricity into heat, shouldn?t the return current be less than the supply?

Bob
 
Re: Energy conversion?

The current is the medium through which the energy is being transferred. It is just like hydraulic fluid traveling through a pipe. The energy is transferred from the pump (through fluid movement under pressure) to the actuator. The fluid then returns to the tank under no pressure. In the same way, current (flowing electrons) transfers (trough movement(or amps) under pressure (volts)) energy from the generator or transformer to the motor or resistor. No current is lost along the way unless there is a ground fault.

In your example, the heat is a result of the electrons being forced through the resistor causing friction/heat and consuming energy in the same amount.
 
Re: Energy conversion?

Originally posted by bthielen:
. . . what energy is actually being converted? . . .
Bob
Click to expand...
The energy used to generate the electricity at its source. Coal, wind, falling water, whatever.

Mike
 
Re: Energy conversion?

"Voltage" is the amount of energy it takes to move an amount of charge from one place to another. "Current" is the amount of charge passing a given point in space during a given period of time. If you multiply those two, you get (energy / charge) times (charge / time), and the result is (energy / time). That gives you "Power," which is the rate at which energy is being supplied or is being used.

That is the sense in which energy is transferred from the source of the voltage to the load. It takes the combination of voltage and current. With a switch open, you will have voltage across the switch, but no current through it. Therefore, the switch is not using up any energy. With the same switch closed, you will see current flowing through it, but almost no voltage drop across it (presuming it has very low resistance and presuming the connecting wires have good electrical contact). Here again, the switch will not be using up any energy.

But consider a single 60 watt bulb that is the only load on a 120 volt circuit. You will have almost all of the source's 120 volts being dropped across the light, and about one half amp of current flowing through it. The combination of these two circumstances is what causes the bulb to use up 60 watt-hours of energy during every hour of its operation.
 
Re: Energy conversion?

So we're not actually converting any of the electrical current into heat. We are generating the heat energy as a result of the friction between the electric current and the heat element.

Since we required a certain amount of current over a given time period to accomplish this we are actually converting the source of the electricity into heat energy as Mike has indicated.

I guess I didn't think that far up the system.

Thanks,

Bob
 
Re: Energy conversion?

I suppose "converting" is a more accurate word that "generating." But either will do for most conversational purposes.
 
Status
Not open for further replies.
Top