Hello, I recently joined ALL ABOUT CIRCUITS.Since am new I will introduce myself .I will start by saying I'm studying at George. T Baker Technical College to become an Avionics Technician. The Courses I have complete are DC, AC, Analog, Digital, Microprocessors; 68000,8085 , 8086, and 8051. I'm half way thru avionics. RF Communication, Microwave,and Fiber optics are the next courses to complete and be able to graduate. I'm also working as a Production Technician. My desire is to become and electrical engineer and will be counting on the info I find here to hep me.Once in a while I forget little details so, I decided to make this into a hobby. I would also like to little by little get rid of all my doubts and have a stronger foundation.
I know the positive side of the power source lacks electrons and the negative has an excess amount of electrons so, electrons flow from negative to positive to fill the gaps.The voltage would be the potential for that flow(correct me in anything that is incorrect please). Now, +5V connected in series to a 100ohm resistor and then to ground is 50mA with that pass thru the connection and 250mW is felt on the resistor. Would it make a difference in the size of the ground if I change the voltage hypothetically to +5000V or even higher. My thought process is that the current would definitely increase creating more power on the resistor but is the ground affected at all? I need a better understanding of ground, from what I know there is two types 1- connected to the negative side of the power source and other one just to a conductive material/metal. Another question would be.. in the first one the electrons go back to the battery but in the second one;the ground that I suppose has a deficit of electrons and as they pass thru it and fill the holes.. will it come a point that the electrons are much more that it can handle?

As you can see I'm pretty confused, please give me some guidance with a source to read about it or if i need to learn the elements for better understanding

so after reading everything I notice kinda of a contradiction to my whole statement.. if positive has a lack of electrons and negative(ground) and excess. electrons flow from ground to the positive? would that mean ground would end up run out of electrons?Now I'm getting myself even more confuse, I think reading about potential differences would help me and I will but anything you can add to help me I will appreciate it.

 

For the moment, forget about what this "ground" thing is. It is actually a catch-all word for many many different things.

When someone uses the "G" word, ask them what kind of ground is this.

As far as "the power source lacks electrons and the negative has an excess amount of electrons" is not true. It is the electric field due to the power source that "moves" electrons. But there is no deficit anywhere.

Electrons will flow from negative to positive. This means a positive current flows from positive to negative, as that is the scientific description and convention, as current is defined as the flow of positive changes from + to -... so negative charges in the opposite direction means the signs (negative on charge and negative on direction) cancel out and you have a positive current.

 

Ok so as I understood from your statement is as the electron moves from negative to positive it creates A change from positive to negative in the opposite direction. Did I understood correctly?

 

Ok so as I understood from your statement is as the electron moves from negative to positive it creates A change from positive to negative in the opposite direction. Did I understood correctly?

Electrons are the actual carrier of the charge and they move from negative to positive.
By convention, positive current flow is defined as positive charge going from positive to negative (which is mathematically the same as negative charge going from negative to positive).
So it makes no difference which you use for most circuits, as the results will be the same.
The exception is when you are studying the operation of vacuum tubes or carrier movement in solid-state devices. For that you need to stay with electrons as the negative charge carrier.

I personally use positive current flow in all my circuit calculations as I find it simpler to visualize (current goes from the positive supply at the top of a schematic to ground at the bottom, and current flows through BJ transistors and diodes in the direction of the arrow).
But you can use whichever convention you like as long as you use it everywhere. Trying to use both at once will likely confuse you.

 

Ok so as I understood from your statement is as the electron moves from negative to positive it creates A change from positive to negative in the opposite direction. Did I understood correctly?

Generally the charge only travels in one direction. In a copper wire electrons go one way, nothing goes the other way. There is never a deficit of electrons since for every electron that leaves one end of the wire another electron enters the other ends.

I shall choose my next words very carefully here.

A potential difference, or a voltage, cannot exist at a point, it needs distance between two points to exist since it is the result of the electric field between these points.

So take two points (or plates here so they are visible) and establish a voltage difference from +positive to -negative between them. Now let some charge carriers free.

Here's what positive charges will do:

Each positive charge element will travel from + to -

Here's what negative charges will do:

Each negative charge element will travel from - to +

What do they have in common? They are both positive currents !

A current has two defining characteristics: how much charge is flowing, and which direction is it going. Obviously charge has a sign, being positive or negative. Not so obviously the direction also has a sign and can be either positive or negative, or in this example either left to righ (positive), or right to left (negative).

One of these currents goes + to - using positive carriers: +charge x +direction => +current
One of these currents goes - to + using negative carriers: -charge x -direction => +current

How do you "let some charge carriers free" as suggested? The easiest way is to put a piece of wire between your points. The outer electrons (negative charge carriers) are easily affected by the electric field due to the voltage difference between the ends.

So it is the voltage that drives the current. One way to remember this is to use an older term for voltage: EMF, or ElectroMotive Force.

Current is an internationally recognized basic unit as defined by the "International System of Units" (SI) . Scientists and engineers need to agree on the basic definitions of "how stuff works." Current is defined as the movement of charge or charge carriers, not just electrons, and there are many things that can carry a charge. The definition of current and the amp unit are quite clear, quite consistent, and oft misunderstood.

You can often tell if someone does not understand what "current" means when they bring up the example of a vacuum tube. There is no fundamental difference between the current inside a vacuum tube and the current running thru a copper wire. Both cases are electrons moving from negative to the positive voltages resulting in a net positive current from positive to negative voltages.