I'm interested in what kind of energy has electric current ?. For everything I taught in school should have kinetic energy because electrons are on a certain potential within the electric field when the switch is closed then the electrons move and the electric current is "generated" which then should have the kinetic energy. And so I was thinking all the time until I came across this article http://amasci.com/miscon/energ1.html which actually tells me that everything I know about the electric current is wrong On the other hand, I wonder if so many books from college ,schools, are spoken in the wrong way It's just a little weird that a huge number of scientists and engineers are actually talking nonsense all the time and so I hope that you can help me clarify my dilemma.

thanks in advance.


The energy of an electric current does not come from the speed of the electrons in a wire. It comes from the fact that they are pushed through the wire by a voltage difference, also called an electromotive force.

Think of a river turning a water wheel. Does the river have to be moving fast to turn the wheel? No. The river turns the wheel because the water is driven by gravity as it flows downhill. The pressure on the paddle from all the upstream water is what turns the wheel. The elevation of the source of the river is the source of energy.

In the same way, an electric current is driven through the wire by a battery or generator. Anything put in its path, like a light bulb, would be able to stop the electron flow if there weren't a voltage pushing the electrons through. That voltage is the source of energy--a potential energy, like gravity. The electric current is a means of transmitting it to the light bulb.

To contrast, the energy in a particle accelerator--where charged particles fly through a vacuum at near the speed of light--is kinetic energy. The work done by the beam at the end of the accelerator happens because of high-speed collisions. Each particle does work because it has high kinetic energy and is no longer accelerated by the time it hits its target. The particles in an electric current in a wire do work because they are pushed through the wire by the voltage. If the accelerator is turned off, the particles already in mid-flight will still do work upon impact. If a voltage in a wire is turned off, all the electrons will immediately stop and cease doing work.

The electrons in a wire never build up kinetic energy because the energy is immediately deposited in the device at the other end of the wires. In fact, the energy travels faster that then electrons. Even though the electrons travel at centimeters per second, an electrical signal travels at about 80% the speed of light, which is why a light turns on immediately when a switch is thrown.

  • $\begingroup$ well, but the waterfall has kinetic energy because the water moves in essence the potential energy must be transformed to the kinetic energy otherwise it is just potential if we speak correctly when the water drops from its height, its potential energy turns into a kinetic and the sum of these two energies gives the mechanical energy that is what drives the water wheel. $\endgroup$ – franjo jovanovič Jan 8 '18 at 9:24
  • $\begingroup$ I've added to my answer. Let me know if it helps. $\endgroup$ – Mark H Jan 8 '18 at 10:12
  • $\begingroup$ I will briefly try to explain what I do not understand the electrons are at a certain potential within the electric field because electrons are moving and they should have kinetic energy if we say the electric current then the electrons move then they must have a kinetic energy as they move or our entire educational system is based on colaosal error $\endgroup$ – franjo jovanovič Jan 8 '18 at 10:27
  • $\begingroup$ Yes, the electrons do possess kinetic energy, and upon bombarding each other in the wire, they produce heat. This is the reason why wires get hot. However, electrical energy is induced by the magnetic and electric field present, which drives the electrons around. This can be also called the electromotive force, which Mark H as correctly pointed out. $\endgroup$ – QuIcKmAtHs Jan 8 '18 at 12:03
  • $\begingroup$ @franjojovanovič If the energy of an electric current in a wire were in the kinetic energy of the electrons, the the electrons entering the anode of a battery should be moving faster than the electrons exiting the cathode. But, electrons actually move at a constant speed through the whole circuit. The moving electrons do have kinetic energy, but that's not a useful way of thinking about how electric circuits work. $\endgroup$ – Mark H Jan 8 '18 at 13:02

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