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Sorry if this is the wrong place, but hopefully someone here can help me

OK so the way I have been taught is that turning off the lights doesn't really actually save electricity due to the fact that all electricity is is electric fields pushing electrons. So when you shut off a light and stop the electron flow, the electric field is still there. So to my understanding the only real way to save electricity is to save it in a battery of some sort. Otherwise it just dissipates in the wires? Can someone pleas confirm or deny this. All that happens when I try and google it is I get a bunch of "10 awesome power saving tips" that don't really help me at all

Again sorry if this is the wrong place. Hopefully this won't take up much of anyone's time.

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    \$\begingroup\$ Turning off unused lights and appliances will save lots of electricity. Basically, the way you have been taught is totally wrong for all practical purposes. \$\endgroup\$ – mkeith Apr 23 '16 at 6:39
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    \$\begingroup\$ Where does the water go when you turn off the tap? \$\endgroup\$ – user_1818839 Apr 23 '16 at 10:52
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    \$\begingroup\$ Actually, pushing without movement only takes energy if your pushing device - like human muscle - has internal losses. Leaning something heavy and rigid against the wall consumes no energy once placed, unless or until it manages to move the wall. \$\endgroup\$ – Chris Stratton Apr 23 '16 at 16:10
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    \$\begingroup\$ It goes to sleep of course :D \$\endgroup\$ – horta Apr 23 '16 at 17:08
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    \$\begingroup\$ Goodnight Kirchhoff, goodnight Watt! \$\endgroup\$ – Chris Stratton Apr 23 '16 at 17:50
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Think of electricity as a handy on-demand way of moving work done in the generating plant into your home's lights and appliances.

If you turn off the switch, you break the circuit, and your lights no longer request this work of the generators. That means they consume a little less fuel, and in the aggregate if a lot of other people go to bed too, some of the generators could probably be shut down for the night.

Of course reacting to demand changes is itself a challenge. Some types of generators can be started or stopped more readily than others, so they make the adjustments with those first. There are also some ways to store excess generating capacity at one hour for use at another - pumping water up hill (that can later generate power running back down), charging huge battery banks, spinning up flywheels - all expensive and having their inefficiencies, but in use or contemplated to some extent. The other approach is to try to activate and de-activate various industrial power uses that don't have to be done at a particular time, to use the capacity of generators when they are under-loaded, and not use it at the peak of a summer day when all those air conditioners threaten to bring the grid down.

As for the power dissipated in the wires, at least for well-behaved loads that basically scales with the amount of work they are moving from one place to another, so when you turn off the light, most of the power lost along the way in moving that work to you stops being lost as well. The only degree to which turning off the light is not effective comes from the fact that a practical generator's fuel consumption is only loosely correlated to its electrical load, and the overall operating expense comes not only from usage, but also from having it available to use. And secondarily, to a very tiny extent, the miniscule power lost to imperfect insulators, induction, etc by having a grid of power lines, transformers, and compensating capacitors cycling at 50 or 60 Hz regardless if they are loaded or not.

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  • \$\begingroup\$ Thank you so much! That's kinda cool then though because I believe then there is a bit of truth to it. It's like how if you spin a crank generator but have it hooked to nothing that energy does go to waist, but lots of the power systems we use have people smart enough to stop cranking or crank slower when needed. \$\endgroup\$ – user107793 Apr 23 '16 at 7:10
  • \$\begingroup\$ @user107793 we can't significantly change the speed at which generators are cranked because we care about the frequency. It's like riding a bike with fixed gearing at 10 mph. You have to keep turning the pedals at the same speed but it's much harder work going up a steep hill than on flat ground. Same with the generator, if its less loaded it will be using less fuel. \$\endgroup\$ – Warren Hill Apr 23 '16 at 9:59
  • \$\begingroup\$ @WarrenHill ok cool. I think I kinda get it now. \$\endgroup\$ – user107793 Apr 23 '16 at 15:04
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    \$\begingroup\$ @user107793: Your first comment suggest that you haven't got it yet. If you hand crank a bicycle dynamo open circuit (lights switched off) no current will flow and it will be quite easy to turn. Turn on the lights and you will feel a lot more resistance. Short it out and it will be difficult to turn. The lesson: work required at generator = electrical energy out + losses. The generator only has to supply the energy drawn by the load. BTW, the energy doesn't go to "waist" or even to waste unless you've got a power station that can't reduce input energy quickly. That gets dumped at source. \$\endgroup\$ – Transistor Apr 23 '16 at 21:04
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What turning the light off means is that you don't consume power in your home (so you don't get billed for it), so the power never gets generated at the power station, and fuel never gets burnt there to make it (which the power company then don't get billed for).

That's what 'saves' means in this context. Most people would call what a battery does 'stores' rather than 'saves'.

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Water analogy is imperfect but good enough.

Pressure = voltage,
pipe flow resistance = resistance.
Current flow = current flow :-).

In a properly constructed water based energy transfer system
power = pressure x current = voltage x current
energy = integral of power over time.

If you have a hydraulic motor on eg a loader it is powered when there is flow and not powered when the flow is turned off.

On both systems pressure/voltage without current/current does not result in energy transfer.

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No hens were harmed in the turning on of any lights.

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In most cases,Modeling Electricity current with a water is a successful example.Assume a bottle of water as a source,you when drinking it as a consumer,and your mouth as a conductor,when you turned it on(take off bottle's plug & drink) you consume the source and when you stopped drinking IT is like YOU Then turned oFF the lights.

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RM edited to above from " ... is like hen turned on the lights."
Is that what was intended?

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  • \$\begingroup\$ "... is like hen turned on the lights." What have chickens got to do with it? The whole analogy is very confusing. \$\endgroup\$ – Transistor Apr 23 '16 at 7:41
  • \$\begingroup\$ @transistor Probably lost in typo rather than translation. Try " ....is like you Then turned OFF the lights". \$\endgroup\$ – Russell McMahon Apr 23 '16 at 12:41

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