- #1
fog37
- 1,568
- 108
Hello Forum,
It is well known that the electrical power dissipated (in the form of heat) by a resistor of resistance R connected to a battery of voltage V is:
P_diss = (V^2)/ R or equivalently P= (I^2)*(R)
Clearly the smaller the resistance R, the more the dissipated power because R is at denominator in the first equation and in the second equation a small R causes a large current I which dominates being squared.
That said, the resistance of wires in power lines is sought to be as small as possible "to reduce losses". But that seems to be against what those two equations above would predict...
Does anyone have any clarification on why the small resistance in power line wires is desirable and can cause the least dissipation?
I know that power lines carry AC power (P=I*V) at a high voltage and lower current. Maybe the fact that the current is low, together with the small R, help produce small losses.
However, I have heard that there is also DC power line transmission which seems to be very efficient...
Thanks,
fog37
It is well known that the electrical power dissipated (in the form of heat) by a resistor of resistance R connected to a battery of voltage V is:
P_diss = (V^2)/ R or equivalently P= (I^2)*(R)
Clearly the smaller the resistance R, the more the dissipated power because R is at denominator in the first equation and in the second equation a small R causes a large current I which dominates being squared.
That said, the resistance of wires in power lines is sought to be as small as possible "to reduce losses". But that seems to be against what those two equations above would predict...
Does anyone have any clarification on why the small resistance in power line wires is desirable and can cause the least dissipation?
I know that power lines carry AC power (P=I*V) at a high voltage and lower current. Maybe the fact that the current is low, together with the small R, help produce small losses.
However, I have heard that there is also DC power line transmission which seems to be very efficient...
Thanks,
fog37