Your analogy of the chocolate bar is not really correct, and personally I hate analogies about electricity.
It would be "less incorrect" if you realised that the battery or mains connection puts more chocolate back, but really afaik the best electrical analogy is water in a circuit where:
Voltage is pressure, current is the amount of water flow per unit time, and resistance is the physical resistance to the flow by friction in the pipes.
There are two fundamental laws from a guy called Kirchhoff:
- Voltage adds up to zero in a loop: the voltage "gains" from a battery or other source are balanced by the "drops" across loads. So a 5V battery adds 5V, and the led and resistor must (together) lose 5V, eg as say 2V in the LED and the other 3V in the resistor.
- There is no net current at a node (a joint). So the current in the battery / resistor / led circuit is the same everywhere: what goes in to a joint must come out. If there's a split, then what comes in must go out in total across the branches.
JimboZA:
Your analogy of the chocolate bar is not really correct, and personally I hate analogies about electricity.
It would be "less incorrect" if you realised that the battery or mains connection puts more chocolate back, but really afaik the best electrical analogy is water in a circuit where:
Voltage is pressure, current is the amount of water flow per unit time, and resistance is the physical resistance to the flow by friction in the pipes.
There are two fundamental laws from a guy called Kirchhoff:
- Voltage adds up to zero in a loop: the voltage "gains" from a battery or other source are balanced by the "drops" across loads. So a 5V battery adds 5V, and the led and resistor must (together) lose 5V, eg as say 2V in the LED and the other 3V in the resistor.
- There is no net current at a node (a joint). So the current in the battery / resistor / led circuit is the same everywhere: what goes in to a joint must come out. If there's a split, then what comes in must go out in total across the branches.
Well thank you for your explanation, current is indeed a physical value that we can see (like the amount of water) well not with our eyes but physically and voltage something that regulate the current (the pression) and well is something that we can calculate but not really seen as the current ... I don't know how to say it but well I understand what you said, thank you
I'm no fan of analogies, but it's probably better to say voltage is something that causes the current not regulates it, and that the resistance regulates it.
But I think you have the idea now...
JimboZA:
I'm no fan of analogies, but it's probably better to say voltage is something that causes the current not regulates it, and that the resistance regulates it.
But I think you have the idea now...
Ok for the idea, the voltage helps to set electrons in motion (which are not moving without voltage) and resistances help to reduce the current. In final, the current is "standardize" in the circuit.
I suppose that at the beginning (in the first few microseconds), the current is established progressively ? Well it's very fast but electrons are moving faster and for each encountered resistance, electrons will slow down until there is a stabilization, I'm a wrong ?
LetMeR00t:
I suppose that at the beginning (in the first few microseconds), the current is established progressively ? Well it's very fast but electrons are moving faster and for each encountered resistance, electrons will slow down until there is a stabilization, I'm a wrong ?
As far as I know it's instantaneous (others may correct me?) unless there's an inductor in the circuit which opposes the change in current, but we'll leave that discussion for another day.
"I suppose that at the beginning (in the first few microseconds), the current is established progressively ?"
Electricity pretty much flows at the speed of light*. Capacitors and inductors can alter current flow as they charge up, or discharge, which can be seen as voltage changes with an oscilloscope. Resistors can alter voltage levels but not alter the current flow as thy do not absorb current or provide current the way caps and inductors do.
- The speed of electric (electromagnetic) field propagation in copper wire is slower than in vacuum by a factor referred to as the velocity factor. The speed of electromagnetic waves propagate in vacuum is 299,792,458 meters per second. The velocity factor for a 12-gauge copper wire copper wire is about 0.951 (according to this source). Therefore, the speed of electricity in a 12-gauge copper wire is 299,792,458 meters per second x 0.951 or 285,102,627 meters per second. This is about 280,000,000 meters per second which is not very much different from the speed of electromagnetic waves (light) in vacuum.
https://www.quora.com/How-fast-does-electricty-travel
CrossRoads:
Resistors can alter voltage levels but not alter the current flow as thy do not absorb current or provide current the way caps and inductors do.
Did you want to say that a resistor doesn't absorb current but only convert voltage into heat ? So for a photoresistor that change the resistor according to the light will absorb more/less voltage but the current will stay the same ?
LetMeR00t:
Did you want to say that a resistor doesn't absorb current but only convert voltage into heat ? So for a photoresistor that change the resistor according to the light will absorb more/less voltage but the current will stay the same ?
The way that caps and inductors do , its a comparison.
Resistors take current and convert it into heat.
Capacitor takes current and converts it to charge, as it does so the PD rises.
They can then discharge this stored charge as a current again.
Boardburner2:
The way that caps and inductors do , its a comparison.
Resistors take current and convert it into heat.
Capacitor takes current and converts it to charge, as it does so the PD rises.
They can then discharge this stored charge as a current again.
Ok so each one of them aborbs current .... It's hard to think that it aborbs current when we know that the current is always the same in all of the circuit and doesn't aborbs voltage when voltage at the beginning is maximal and null at the end ^^ Don't you ?
I think you need to google on.
POWER
ENERGY
CURRENT
VOLTAGE
And try to understand the relationship between them.
Then look at the basic passive components and how they work.
Resistors, Capacitors ,Inductors.
Inductors resist the change of current.
Capacitors resist the change of voltage.
Boardburner2:
I think you need to google on.
POWER
ENERGY
CURRENT
VOLTAGE
And try to understand the relationship between them.
Then look at the basic passive components and how they work.
Resistors, Capacitors ,Inductors.
Inductors resist the change of current.
Capacitors resist the change of voltage.
Ok thank you for your advice 