# Electrical Signals and Digital logic design

#### David_Elbert

Joined Aug 3, 2017
9
I am an electrical engineer, my first question is that how electric signals move inside wires? how to initiate the electrical signals knowing that in order for the electron to move in a circuit, we need a continuous voltage which is not the case in the signals.

my second question is that in the basic logic gates in a typical computer, are the inputs of the gate always have a constant supply of current or voltage or they are only signals

thanks

#### WBahn

Joined Mar 31, 2012
26,301
So ... where is your electrical engineering degree from?

#### David_Elbert

Joined Aug 3, 2017
9

#### WBahn

Joined Mar 31, 2012
26,301
So you are not an electrical engineer, but rather an electrical engineering student. That's significant because the amount of background knowledge expected for each is quite different.

Where are you at in your EE studies? Do you understand the relationships between electron motion, electric fields, and voltage?

What is YOUR understanding of what an "electric signal" is? You use the term in a way that implies that you might think it is something other than what it is.

#### David_Elbert

Joined Aug 3, 2017
9
I am a sophomore student .. in fact, I do not understand what is the electric signal is but I fully understand the four terms you introduced

Joined Jul 18, 2013
21,630
, my first question is that how electric signals move inside wires?
..... which is not the case in the signals.
.......or they are only signals

thanks
What do you perceive 'Signals' to be?
Max.

#### David_Elbert

Joined Aug 3, 2017
9
a group of electrons that move equally along the wire

Joined Jul 18, 2013
21,630
we need a continuous voltage which is not the case in the signals.
Explain this statement?
Max.

#### David_Elbert

Joined Aug 3, 2017
9
in a closed circuit, we need to a constant voltage to move a single electron from one place to the other .. how we initiate the signal

#### MrChips

Joined Oct 2, 2009
22,099

#### MrChips

Joined Oct 2, 2009
22,099
in a closed circuit, we need to a constant voltage to move a single electron from one place to the other .. how we initiate the signal
What is your definition of "signal"?

#### David_Elbert

Joined Aug 3, 2017
9
I have said that before ...

#### WBahn

Joined Mar 31, 2012
26,301
in a closed circuit, we need to a constant voltage to move a single electron from one place to the other .. how we initiate the signal
Actually, we don't. For instance, in a superconducting coil electrons will flow continuously without any voltage at all.

For your purposes in this context, a "signal" can probably best be thought of as any phenomenon capable of conveying information. Also, in this context, it is probably reasonable to think of the chain of events associated with an electrical signal something along the lines of the following:

Something causes some electrons to physically move. Perhaps it is a bunch of chemicals in a battery. Perhaps it is light or heat interacting with certain substances. Perhaps it is an electromagnetic wave interacting with an antenna. Whatever. The movement of those electrons creates a net electric field in their vicinity and, in response to that, other electrons move. The movement of those electrons cause changes in the electric fields which cause other electrons to move. The result is a progression of electron motion. While the individual electrons themselves move only slightly and slowly, the influence of the electric fields their motions create (which is nothing more that Coulomb's Law, when all is said and done) propagates at the speed of light.

Changes in whatever is causing the electrons to physically move is what generally constitutes the information we are interested in, and the patterns to the changes they make, in turn, to the electric fields are what constitute the electrical signal that we detect and measure in order to access that information.

#### MrChips

Joined Oct 2, 2009
22,099
I am an electrical engineer, my first question is that how electric signals move inside wires? how to initiate the electrical signals knowing that in order for the electron to move in a circuit, we need a continuous voltage which is not the case in the signals.

my second question is that in the basic logic gates in a typical computer, are the inputs of the gate always have a constant supply of current or voltage or they are only signals

thanks
Did you know you can move electrons with sunlight?