If you have ever wondered how stuff work and how engineers choose the correct values for circuit then here we will look at how we do that.
Firstly there have been humans that have dedicated there lives to finding's so that the future generation can build upon there knowledge and use it to make the world better and more efficient, I give thank you to there finding's and that if it wasn't for there lives and there work we wouldn't be were we are now.
Within a basic circuit you have different elements that work with and against each other to produce whatever it is you want to produce the main ones we will look at are as follows.
Shown as I, We may know current as flowing to some where but current doesn't actually go anywhere in a circuit the electrons do, and as we have been taught current flows from + to -, but electron flows from - to +. We need to imagine the flow of electricity as this Electrons carry a charge and moving the charge results in current, electrons are the most common charge in electronic circuits but other elements have charges too (protons, positrons, ion's, Impedance etc) we stick with electrons as the purpose of electronic theory.
I = Change in charge / Change in time = Amps
This was found by Alessandro Volta (1745-1824), the Voltage symbol v/V is defined as a electrical difference between 2 points. For electrons to move we need a force in order to push them from one place to another, there is a spacial name for this and it is called electro motive force or EMF, If we take a battery we know from this we have 2 plates when we connect the two plates together we get a closed circuit and we create current flow, if we plate things in its path the energy that it takes to move through the object will be dissipated in whatever object is in it's place, such as a Resistor will dissipate Heat.
V = Change in work (Energy) / Change in charge = Volts
We can thing of wattage as power and visa versa, if we lift a 1kg weight up 1 meter we would need 9.8 joules of energy, if we move the 1kg weight up quickly we would need to supply that energy in a shorter space of time, so the power expanded is greater than if it is lifted slowly. Moving quickly means we would have high current flow and moving it slowly means we would have low current flow.
P = Change in work (energy) / Change in time = watts
Everything has a equal to or opposite reaction (Newton's Law), the opposite of current flow is resistance, If we did not have resistance electrons would keep accelerating forever and the current would grow to infinity (Warp drive can be done). Resistance is measured in Ohms, named after Georg Simon Ohm, his work leads us to the Ohms Law or where we have a pyramid Resistance Ω = Voltage / I Current
the Earth, Ground or neutral have a neutral difference 0v if we create a plate which has potenital of 1V when we connect the plate to ground Electrical Current will Flow