My comments in bold, I won't touch on every topic but will try to keep it a basic discussion.
Thank you for the added info and discussion
There are some misleading facts in this thread.
So I will try to correct them.
And it's good to explain first how energy is carried from hard sources (wall receptacles) when you understand this, than you will move on batteries(soft sources)
1. Voltage, denoted oftenly as U is measured in Volts(V) - is the primary force that causes electricity to work, it polarizes electrons in conductors connected to the voltage source and they are ready to flow once the circuit is closed.
Not really accurate, at least not the way it's stated here. Electric force and voltage are not the same thing (though you can convert between the two). I'm trying not to get into the actual math/physics breakdown because I don't want to go on a 2 page explanation of it all, but voltage is a function of distance and the electric field, which is a function of electric force and distance. Also, perhaps you mean something else by polarize, but voltage does nothing with polarizing electrons, electrons are inherently negatively charged (there is something called electron spin, but that's not what we're talking about). Keeping it simple, voltage is a potential measured across difference, much like newtonian Potential Energy in regards to height and mass.
2. Current, denoted as I is measured in Amperes(A) - is series of moving free-stream electrons in electrically-conductive materials, when they are exposed to voltage source. Making it carrier of electrical charge, constant flow of electrical charge transfers energy. There are 2 types of current, the Alternating current(AC) and Directive Current(DC). About when and why they are used later. What is important is that current starts to flow only when circuit connected to voltage source is closed.
This is more or less true. The only thing I'll point out is that a circuit doesn't have to be connected to a 'voltage source' per se (as in a battery or something) for current to flow, all you need is a separation of charges which creates enough potential to overcome whatever dieletric is separating them. There are also such things as current sources that provide constant current with varying voltages. Electrons can also travel on their own (in a way) if given the chance, but this isn't the right place for that kind of discussion.
3. Power(electrical energy), denoted as P, also known as Performance and measured in Watts(W) - is universal unit for describing how much energy is required to run particular device.
This is pretty much true, though just in case it's not clear to everyone, energy and power are actually two separate but linked things (power is time dependent; energy typically measured in joules).
It is the only important factor we need to overcome challenges we are working on when constructing and deploying electrical appliances. All other units, including voltage, resistance and current are here only to optimize efficient performance of appliances.
This is just false, sorry.
And now let's go on how voltage and current work together.
Voltage is force that cause current to flow because it polarizes the electrons inside the conductors,
Covered above. I think the point you are trying to make is true, perhaps just different phrasing is necessary.
when you close the circuit, they start to flow and start transfering electrical energy to the devices within the closed circuit, creating current, the multiplication of voltage and current will tell you how much energy (power, not energy) in watts we are using. The correlation between voltage and current depends on power drawn. For example if your coffee maker has 120V/7A rating on its label it draws 840W from wall receptacle. If you would however connect it to 230V(in case its designed for that) it would draw only 3.6A, but the transfered energy would still be same 840W. So in linear correlation with lower voltage the higher current is needed, if the voltage is higher than current is automatically lower just to hit the required energy for the device.
This is not necessarily true. Yes, in the example you gave, it is true due to the voltage difference in different countries, but usually the amperage rating on an electronic device is the max amps it can handle. Power is derived from voltage and current, not the other way around.
It depends on the purpose of device how much energy it uses, the devices required for heavy applications need much more power than the household ones.
Above mentioned coffee maker draws 840W which is quite alot of energy, because it needs to boil the water, it must generate alot of heat, as the current that flows through the resistive spiral must be high in order for it to become hot and therefore heat the water for coffee.
The cellphone a small lightweight device, while charging uses no more than 5W of energy.
Light rail vehicle which is quite heavy on its own and travels at high speeds draws as much as 500kW(500 000W)of energy and is by that way also powered under higher voltage(oftenly from 600 to 2500V) and uses current as much as 800A when accelerating and braking.
Electric locomotive uses upto 4000kW, and may be connected to catenary powered by as much as 25kV(25 000V) and utilize current upto 1500 A.
On other hand, the nuclear reactor in power plant has performance of 950MW(950 000 000 W). (nuclear reactors can actually top 1 GW, though most are under)
What I mentioned now were only maximal values, the energy required changes depending on how much load the device has to carry on.
The uncoupled locomotive will draw only 50kW from catenary, when attached to a long fully loaded freight train it will use its 4000kW like nothing.
The idle computer draws about 50W, when you turn on the games or heavy programs it may go as high as 1kW depends on the parts inside.
Coffee maker or light bulb are passive and they use same amount of energy everytime they are turned on.
Again, just for clarity, most of the examples you mentioned will have a power factor involved as they are not purely DC systems, so it is not simply P = I*V, but it would be the 'ideal' power times the relevant power factor.
If you need to know something about electricity feel free to ask but it's way too much to just write it here all
Or if someone knows better correct me if I'm mistaken.
Thank you for the added info and discussion
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