Can electricity flow along a cable of any length.?

Question

ie if a strong current was sent along a cable, say 100 miles long, would any current come out at the other end.?

Answer 1

There are transmission cables that are more than 100 miles long. Every practical conductor has resistance. That resistance times the current flowing through the conductor determines the voltage drop in the cable.

Resistance x Current = Voltage Drop

You'll have the same "current" flowing out the other end, it will just be at a lower voltage.

Here is a water analogy to help understand the terms. Think of the transmission cable as a long garden hose. The water pressure at the at the spigot is the voltage. The resistance of the walls of the hose is like the resistance of the conductor. The water flow rate (i.e. gallons per minute) is the current flowing through the circuit.

There are no leaks in the hose, so every gallon comes out the other end. The only difference is that it has substantially less water pressure.


It is not uncommon for local utilities to have distribution feeders that are 40+ miles from the substation to the last customer.

Answer 2

It depends on the size of the cable. The thicker the cable the more that makes it to the end. This is due to the fact that a small cable that has electricity flowing through it has a higher resistance than a larger one which causes it to heat up. The heat give off because of the resistance of the cable is really electrical energy being converted to thermal. I'm pretty sure that the way that power companies counter this is that they really jack up the voltage and drop the current and then simply reverse the process once the electricity arrives at it's destination.

Answer 3

to put this in simple terms, the line can modeled as a series resistance. So according to ohm's law, thats how much voltage this line will drop. In power systems, u have to consider other things like line inductance and capacitances.
this is why Transmission voltages are so high.
there is this story, at one airport, the conveyors belts were failing so they got one consulting firm to find the solution. that firm thought that it was a high frequency signals that were ruining the motors so they put in filters. Worked for a while but the motor drives failed again. the airport lost faith in this firm and hired another firm, which discovered the main problem which was the long cable length that ran from the power source to the drives. this cable dropped alot of voltage.
so to answer ur question, if u need 100 amps at one end, and the cable is that long, not much useful work can be done coz current will have been very limited.
If the ckt is not loaded, meaning there is nothing to draw power, yes u will get the same amount of current but there is no ckt thats not loaded.

Answer 4

The voltage may drop along the line but the current in the line should be the same from end to end unless power is being "tapped off" here or there.

The resistance of copper is low but it is not zero so there is some voltage drop along a long transmission line. This problem is minimized by transmitting at a high voltage (when the voltage is stepped up the current is stepped down).

The power lost along the line is
p = I^2 R
Where R is the resistance of the line.

Answer 5

Yes there may be current that will come at the other end but that current is not as strong as it was before thatis from the source. This is due to voltage drop on the cable as current passes through because of resistance.

Answer 6

a wire that has a gauge #1 will have the least resistance while smaller gauges will have more. it is not length but inductance that shows how well a wire can maintain it current.

Answer 7

This is done every day by commercial power distribution systems in use today.

Answer 8

why not?