Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Electronics newbie

Status
Not open for further replies.

josephmichael

New Member
Ok, I'm working on my degree in electronics but still a newb. Sometimes I have trouble grasping things because it is so abstract. Here's my question, lets say you have a series circuit with a 5v emf, 2 resistors, both with a 2.5v drop. In a series, voltage drop, circuit the voltage drop always equals the supplied voltage, well if you "drop" 5 volts how does the current continue to travel through the rest of the circuit without the voltage to push it? I know how to go the math in circuits but not getting this. I know I am looking at it wrong but can not get it. Thanks for any help...
 
The rest of the circuit (source, wires, etc) has CERO resistance.

Then their voltage drop will be E = I R = I cero = cero.
 
RLC Circuite

Please Design RLC circuit if
R=100 ohm
l=0.1 mH
c=10 uF ( micro Farad)
F=60 Hz
VT=120Vp (Pleas convert Vp to rms Value)
Find Zt , It cos fi, Critical Frequency Fr and Fi
After calculating value fr please explain behavior of the network with Wave form
 
The voltage is the force pushing the electrons.
The current is the number of electrons moving past a point, per second.
The resistance is the opposition to that movment that the voltage has to overcome.
The goalpost is....no wait :)

Your force is 5 volts overcoming the resistance of the two resistors in series.

With this force pushing electrons through this resistance, E/R electrons will pass a
point in the circuit in one second. Edit: Wrong. It will cause E/R Coulombs of electrons to pass a point in the circuit in one second.

The circuit is a loop and the point is anywhere in that loop.
 
Last edited:
So the current keeps flowing, doesnt the voltage push the electrons? If you have 2 resistors and you lose 2.5v at the first resistor you will only receive 2.5v at the second resistor? Then you lose another 2.5v, how does the current continue to be pushed if all voltage was dropped.

Thanks for all of you guys help, it's opening up my eye somewhat...:)
 
Your asking, does the voltage push the electrons?
My first sentence tells you "The voltage is the force pushing the electrons."

You are asking the same questions.
Please read it again and try to understand.
I'm trying to tell you how to look at what is happening.
Try to see it another way, your way is not working...yet.

Remember, it's a loop. If the electrons are "pushed" out of a battery, the job is not done until they return to the other end of the battery.
 
Last edited:
The resistors only drop voltage because there is a current flowing through them.

If we have an open circuit, say the wire from the last resistor to the battery (EMF source) was disconnected. Measuring from the -ve terminal of the battery to the +ve terminal, using a voltmeter, we find 5 volts, at the junction of the two resistors we still find 5volts and at the disconnected end of the second resistor we still find 5 volts, because no current is flowing.

When we make the connection, current* can flow from the +ve terminal of the battery, through the first resistor, through the second resistor and back to the -ve terminal of the battery.
It is the same current which flows all the way around this circuit, there are no branches to the circuit, the same current flows in each element of the circuit.
If we use our voltmeter again, we measure 5v at the +ve terminal of the battery, 5v at the top of the first resistor, 2.5v at the junction of the two resistors, and 0v at the bottom of the second resistor.

This description assumes that our connecting wires are perfect and have zero resistance.
In the real world the wires will have resistance, so if we have a voltmeter with enough resolution we may see something like this:

At the +ve terminal of the battery 5.000volts
At the top of the first resistor 4.990 volts
At the junction of the two resistors 2.500 volts
At the bottom of the second resistor 0.010 volts

There is 0.01volts to drive the current through the resistance of the wire back to the battery!

Does this help?

JimB

* I am assuming conventional current flow and am not going to get into a p*****g contest about conventional current vs electron flow.
 
Last edited:
Ok, here is what I have so far, please bare with me I promise I'm not high...Although it would probably make this easier.

The only thing that flows through a circuit is electrons, nothing else, not electrons, current and voltage, just electrons in a manner of speaking.

Current is just how many electrons are flowing, 1 amp of current just means that 1 coulomb, 6.24x10e18 electrons are flowing through the circuit at a specific point every second but it's still electrons.

This must mean that voltage does not flow through the circuit either. So what is voltage? It is the difference in electrical potential between 2 points. More electrons on the neg and too few on the pos side which causes the neg side to push and the pos side to pull, right? This means that voltage is the amount of work that would need to be done to an electron to move it from one point, through an amount of resistance through another point? If you have "voltage drop" through the resistor, the circuit, as a whole, has 5v of pd? The voltage is only gone mathematically? A load of 2.5 Ω means that it takes that much energy to move electrons through it. Without the load the current would be too high for the circuit.

I'm still a little confused on the voltage but hope I am getting on the right track.
 
Last edited:
After I read over you post again, Flat5, and thought about what voltage and current actually were I read your post again, I believe with a little more understanding. Thanks

JimB, thanks, it helped, didn't matter if it was conventional or electron flow i was just trying to figure out where this mysterious voltage was going.

Thanks all, if you want to add anything else, that would be great...
 
Your getting there. Don't confuse force with power. Power is work DONE.
E x I = Power
Voltage is the force applied to do the work. It may or may not be enough to get the work done. It will cause a certain current to flow through resistance.
 
Thanks Flat5,
Ok, sounds good, voltage is the force applied to do work...

Maybe this question will help me understand a little better, if I can word it right. Where does this force, voltage, come from. I know potential difference more neg than pos etc....
Voltage makes electrons move, correct? The greater the voltage the greater the current, correct? So in simple terms where does this force come from? You have a 1.5v battery and a 9v battery, the 9v has more force? How? why? where does the force come from? Do you store more electrons in a smaller space? I mean I'm sure that's not correct but do you see what I'm asking. Using the water analogy you get water pressure by placing water in a high tower, water tower, how is this voltage, pressure, produced? Thanks again bud you have really helped so far.
 
See if this only makes the subject even more confusing:
Electrical curriculum: What is Voltage?

Voltage, also called electromotive force, is a quantitative expression of the potential difference in charge between two points in an electrical field. A voltage produces an electrostatic field, even if no charge carriers move (that is, no current flows). As the voltage increases between two points separated by a specific distance, the electrostatic field becomes more intense. As the separation increases between two points having a given voltage with respect to each other, the electrostatic flux density diminishes in the region between them. Same as magnetism.

Part of the explanation is that when a current exists, electrons are moving from atom to atom. When there is no current but voltage potential, electrons are in over abundance someplace and want to get home to a place that is missing them.

You could study atoms and valence a little. It might help.

Consider a battery. The chemical process in the battery creates a surplus of electrons at the negative terminal and a deficiency of electrons at the positive end (due to the fact that absence of electrons does not automatically indicate presence of positive charge, unless we consider this terminal charged with positive ions). The potential difference or voltage between these two points is the "push" that the battery can supply to a conductor that may connect the two terminals.
 
Last edited:
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top