Lots of doubts in elementary electronics

[SinCronus]

Hello,

My Situation
I slacked off a lot in school and college and its only now that I'm serious about electronics(currently I'm free). I figured that starting from scratch would be the best way to clear up my muddled understanding of electronics(basically and joining a good forum would be of immense help as well to get help from knowledgeable people. So, I've started hitting my books and the internet.

The purpose of this thread
During the course of this period, I would like to confirm things with you guys so that I can proceed with confidence to other topics. That is, whatever doubts I may get while reading the material and stuff, I post questions on it and get them clarified. Along with questions, I will also post my current understanding of that topic so if its flowing in the wrong direction (no puns intended :lol, I can correct it. If you want to, you can also assign a score to my level of understanding. Like "you've understood it perfectly! 10/10".

Instead of creating a thread for every question I have every now and then, I figured it would be best a create a single thread and keep bumping it whenever I have a doubt or want to confirm things. Please try to give real world examples as much as possible and keep the technical terms to a minimum. Another reason for this is to discuss these questions with many people.

What do you get?
Err...satisfaction? A chance to test out your basics? By answering them, I guess you could say you'd probably improve your knowledge about electronics too. Right now these are fundamentals (so it won't help much) but I hope in the near future I would be able to discuss some pretty advanced topics with you guys.

So without further ado, here's my first set of doubts, on the topics of "Current and Voltage".

DOUBTS/QUESTIONS/STUFF
1. A very elementary question.
What is current and what is voltage? Differences between them and what comes first.
I require the answer in very simple terms please. Real world examples if possible instead of technical definitions.
MU (my understanding):
Current is the flow of electrons. For an atom of any material, it has subatomic particles like neutrons, protons and electrons. The electrons revolve in shells around the nucleus which holds the
protons and neutrons. Protons are +ve charged, neutrons are neutral and electrons are -ve charged.
Since unlike charges attract each other, there is a force of attraction between the electrons and protons which binds them together. The closer the electron is to the nucleus, the greater the force of attraction. So, the electrons farthest away from the nucleus have less force of attraction and on applying sufficient force/energy can be made to quit the atom and become a free flowing electron. There can be many free flowing electrons.
In a material, there are multiple atoms for which there would be multiple free flowing electrons and if there is a movement of these electrons due to application of some energy, this is known as "Voltage".
Voltage/Potential is basically in very simple terms the energy applied to move the electrons.


2. Is my understanding on the mark? The usual definition of voltage I've come across "is the amount of work done to move a charge" or something similar.
My next doubt is: "Where exactly are we moving the charge?" How does it fit in with the electron story I wrote above?
Moving on to real world, what does, say 15V, translate to? Meaning 15V is the work done to move a charge where? Comparing it with say 30V, what is the difference? Meaning, does 30V move the charge a larger distance or does it do something else?

3. Is there a difference between electric potential and Voltage? And what of emf and voltage? Can we use these terms like emf to refer to voltage and vice-versa? I've seen some books equating voltage with emf sometimes and sometimes not so I'm confused.

REQUEST
Please answer with as little technical terms as possible. I get really confused when a lot of them are thrown around.
I'm also not forcing anyone to answer so if you have time to respond to a complete newbie like me battling with the fundamentals, then please do so.

Thanks,
Sin

 

[jiripolivka]

Hello,

My Situation
I slacked off a lot in school and college and its only now that I'm serious about electronics(currently I'm free). I figured that starting from scratch would be the best way to clear up my muddled understanding of electronics(basically and joining a good forum would be of immense help as well to get help from knowledgeable people. So, I've started hitting my books and the internet.

The purpose of this thread
During the course of this period, I would like to confirm things with you guys so that I can proceed with confidence to other topics. That is, whatever doubts I may get while reading the material and stuff, I post questions on it and get them clarified. Along with questions, I will also post my current understanding of that topic so if its flowing in the wrong direction (no puns intended :lol, I can correct it. If you want to, you can also assign a score to my level of understanding. Like "you've understood it perfectly! 10/10".

Instead of creating a thread for every question I have every now and then, I figured it would be best a create a single thread and keep bumping it whenever I have a doubt or want to confirm things. Please try to give real world examples as much as possible and keep the technical terms to a minimum. Another reason for this is to discuss these questions with many people.

What do you get?
Err...satisfaction? A chance to test out your basics? By answering them, I guess you could say you'd probably improve your knowledge about electronics too. Right now these are fundamentals (so it won't help much) but I hope in the near future I would be able to discuss some pretty advanced topics with you guys.

So without further ado, here's my first set of doubts, on the topics of "Current and Voltage".

DOUBTS/QUESTIONS/STUFF
1. A very elementary question.
What is current and what is voltage? Differences between them and what comes first.
I require the answer in very simple terms please. Real world examples if possible instead of technical definitions.
MU (my understanding):
Current is the flow of electrons. For an atom of any material, it has subatomic particles like neutrons, protons and electrons. The electrons revolve in shells around the nucleus which holds the
protons and neutrons. Protons are +ve charged, neutrons are neutral and electrons are -ve charged.
Since unlike charges attract each other, there is a force of attraction between the electrons and protons which binds them together. The closer the electron is to the nucleus, the greater the force of attraction. So, the electrons farthest away from the nucleus have less force of attraction and on applying sufficient force/energy can be made to quit the atom and become a free flowing electron. There can be many free flowing electrons.
In a material, there are multiple atoms for which there would be multiple free flowing electrons and if there is a movement of these electrons due to application of some energy, this is known as "Voltage".
Voltage/Potential is basically in very simple terms the energy applied to move the electrons.


2. Is my understanding on the mark? The usual definition of voltage I've come across "is the amount of work done to move a charge" or something similar.
My next doubt is: "Where exactly are we moving the charge?" How does it fit in with the electron story I wrote above?
Moving on to real world, what does, say 15V, translate to? Meaning 15V is the work done to move a charge where? Comparing it with say 30V, what is the difference? Meaning, does 30V move the charge a larger distance or does it do something else?

3. Is there a difference between electric potential and Voltage? And what of emf and voltage? Can we use these terms like emf to refer to voltage and vice-versa? I've seen some books equating voltage with emf sometimes and sometimes not so I'm confused.

REQUEST
Please answer with as little technical terms as possible. I get really confused when a lot of them are thrown around.
I'm also not forcing anyone to answer so if you have time to respond to a complete newbie like me battling with the fundamentals, then please do so.

Thanks,
Sin

You can have simple answers and quite complex ones. Best to learn is to find a good textbook of high-school physics.

Simple answers: Based in atomic physics we think there are charges in all atoms. Upon an agreement we name the core positive (protons) and the "skin" negative (electrons).

After a long study it was determined that certain atoms have "free" electrons in their top skin level, and as such electrons can be easily displaced from their atoms, we name such materials conductors.
Other atoms have their top skin level filled with electrons and do not release them easily, so we call them insulators.

In a conductor, charges (electrons) can move if there is a force in the conductor or outside. Moving charges we name "current" and over time instruments were developed to measure the current.

The force to move charges we name the "potential". It can come from external charges or from a magnetic field. Technically we build circuits in which currents can flow, and between certain points the difference of potentials is named "voltage". Again, we have instruments to measure the voltage.Mr.Thevenin and Kirchhoff developed circuit laws by which we can understand resistances that push again currents, and voltages that develop.

We have understood that everywhere around there is the electromagnetic field (one of its forms is light). If the charges in conductors do not move, they generate a static field. If they move, an alternating electro-magnetic field exists around, and can propagate away from the source. Then we understand the field exists as waves, also in a vacuum.

All above understanding was created by many scientists and inventors over last ~200 years. From a pure magic we now have a powerful tool to transmit energy on distance, to communicate, and more.

Again-take a good high-school textbook of physics, and do read it well.

 

[ahmed-agt]

Hi friend!
To ME.... I think reading is essential in every thing you want to know about, meanwhile, electronics or engineering can be well appreciated when you apply them. in all, for this process not to be boring; I will suggest that you should pick any simple topic or applied topic and work on. Example power supply, step down type, rectification, filtrating in power, linear regulators and zener diodes. These caries a lot of theories and practical examples that you need to prove yourself.

However, LEDS and Diode, transistor as switch & Amplifier, will guide you more on semiconductors, while your knowledge in power supply will help you power these stages.

Good luck.

 

[SinCronus]

You can have simple answers and quite complex ones. Best to learn is to find a good textbook of high-school physics.

Simple answers: Based in atomic physics we think there are charges in all atoms. Upon an agreement we name the core positive (protons) and the "skin" negative (electrons).

After a long study it was determined that certain atoms have "free" electrons in their top skin level, and as such electrons can be easily displaced from their atoms, we name such materials conductors.
Other atoms have their top skin level filled with electrons and do not release them easily, so we call them insulators.

In a conductor, charges (electrons) can move if there is a force in the conductor or outside. Moving charges we name "current" and over time instruments were developed to measure the current.

The force to move charges we name the "potential". It can come from external charges or from a magnetic field. Technically we build circuits in which currents can flow, and between certain points the difference of potentials is named "voltage". Again, we have instruments to measure the voltage.Mr.Thevenin and Kirchhoff developed circuit laws by which we can understand resistances that push again currents, and voltages that develop.

We have understood that everywhere around there is the electromagnetic field (one of its forms is light). If the charges in conductors do not move, they generate a static field. If they move, an alternating electro-magnetic field exists around, and can propagate away from the source. Then we understand the field exists as waves, also in a vacuum.

All above understanding was created by many scientists and inventors over last ~200 years. From a pure magic we now have a powerful tool to transmit energy on distance, to communicate, and more.

Again-take a good high-school textbook of physics, and do read it well.

I'd have much appreciated a point to point reply to my queries but this works too I guess. In any case, thank you very much for replying. Did you notice anything particularly wrong in my explanation?

So if I'm getting you right, 'Potential' is the name of the force which is applied to make the charges move. In a circuit, there may be varying amounts of force applied at different area/regions and the difference between these forces between two points is 'Voltage'. These differences are due to resistances and other stuff.
(That makes me ask: what is the difference between say 15v and 30v? Voltage is the difference of potentials. So does 15v mean there is a difference of 15 between the two forces/potentials?40v and 20v means a difference of two between the pairs of potentials)

Everywhere around us there is an EM field which exists as waves. If the charges do not move, conductors have a static/unchanging field. If they move, a field exists which can propagate/move away from the source. Err...you didn't mention what this does.

A question based on this: if sufficient potential/voltage say a million volts is applied to an insulator, will it conduct? Or rather, can an insulator conduct with sufficient force applied to it? I understand they are bad conductors since they do not release electrons easily.

I am going through these books of course(most of which I've sold/given away) but that really wasn't my point of creating this thread. Whatever I'm learning through these books, I wanted to confirm with you guys. Basically, I've learned/interpreted this in so and so manner and wanted to check if my interpretation of my texts is correct.

In any case, thanks for replying once again. Could you also answer my third question about emf and stuff?

 

[KerimF]

Producing the electrical and electronic components usually requires a good knowledge of Physics related to electronics.

On the other hand, designing and building electrical and electronic boards that are formed by these components requires the knowledge of the electrical/electronic rules and formulas only.

I personally don’t believe (long story) in some theories in physics as “the electric current is the movement of electrons (called free ones)”. But this didn’t prevent me to be professional in designing useful electronic circuits/boards (as a private business). For example, in elementary electronics, asking why voltage (V) is equal to (I*R) is irrelevant. It is better knowing instead when this formula could be used and how.

Is there a difference between electric potential and voltage?

Practically speaking, they are equivalent. To my knowledge, the expression of "electric potential" or "potential" is usally used in static electricity.

Is there a difference between emf and voltage?

Also, practically speaking, they are equivalent. But EMF usually refers to the voltage generated by the magnetic force according to faraday's law.