The concept of potential difference is very important topic of current electricity. If you didn’t know or understand this topic, then it is very difficult for you to give the explaination of the question, why does electrons move in electrical circuit after supplying electricity?
So it is very important to understand the underlying concept of potential difference. Once you understand the concept of potential difference , then you are able to give the answers of various questions of current electricity.
So let’s starts with a question.
What is the main purpose of electricity? Many of you can give the different answers, but If we talk about the main purpose of electricity then the main purpose of electricity is to create potential difference in the electrical circuits. All the big machine which are run on electricity, the source do nothing but they only create potential difference and all the rest activity( motion of electron and creation of current and many more) is done by the potential difference.
WHAT IS POTENTIAL DIFFERENCE
Let’s understand the potential difference in simplest way-
For understanding potential difference in simplest way, let’s assume that you are bringing a unit positive charge +q from infinite to a point A in the region of electric field E , such that you are not accelerated while bringing that charge.
If you’re bringing something from infinite in the opposition of electric field, then you must have done some work W1 on the charge or work is done by the charge.
So if you bring a unit positive charge +q from infinite to a point A in the electric field E , without acceleration, then that point A in the electric field attained a potential called electric potential due to charge +q.
Now you again goes for infinite and bring a unit positive charge +q , and put it to point B in the region of electric field without acceleration, then the point B in the electric field attained a potential called electric potential due to charge +q.
Now again if you’re bringing something from infinite in the opposition of electric field, then you must have done some work W2 on the charge or work is done by the charge.
And the potential difference is nothing but it is the difference between the potential at point A and potential at point B.
Potential at point A is
V1 = W1/q and at point B is = V2 = W2/q
Potential difference P.D = V1 – V2 =(W1-W2)/q
V = V1 – V2 =(W1-W2)/q = W/q
WHY DO ELECTRONS MOVE IN ELECTRIC CIRCUIT AFTER SUPPLYING ELECTRICITY
So far we have understood that what is potential difference and now it’s time to understand that
Why does electron flow in electrical circuits after electric supply?
We know that every cells , battery and every electric source has two output or terminal one is (+) terminal and second is (- )terminal the positive terminal is the point where electric potential is very high and negative terminal is the point where electric potential is lowest or zero.
When potential difference is zero all electrons remains at the rest , there was no motion in them, but as the potential difference become highest, the positive terminal or you can say point A, reaches to its maximum potential height and negative terminal (point B) reaches to its minimum potential height that is zero. This makes electrons move automatically from highest potential point to the lowest potential point.
You all of you must have seen or even tested with tester that in home electrical switch board one pin socket has supply of electricity but in second it doesn’t.
This creates the maximum potential difference to flow the electrons in the circuit, the pin socket which have electric supply have the maximum potential and the pin socket which have no electrical supply have 0 potential.
This is the reason of flow of electrons in electrical circuit.
NOTE : Above diagram only illustrates the cause of electron motion, don’t use above diagram to show the current motion and it’s direction.