|Author: Rohit Sharma 18 Jul 2012 Member Level: Silver Points : 5 (Rs 3) Voting Score: 0|
It is a very easy question, but generally students have doubt about the direction of current in their mind.
First of all, let me tell you the exact definition of Current, it is defined as the rate of flow of charge. Thus the direction of current should be given as the direction of charge, i.e. positive charge, thus if negative charge will flow, the current will definitely carry the opposite direction.
In another way,
current can be stated as,
where "I" is current
"q" is charge
"t" is time
now in the above equation,
if the "q" is positive, the "I" will also be positive.
but if the "q" is negative, then "I" will also carry negative sign which implies opposite direction.
As electron carries negative charge, thus current will definitely have opposite direction.
Always remember, though current has a direction, still it is not a vector quantity because it do not follow the addition and subtraction laws of vectors.
Hope you understand.
|Author: krypt 18 Jul 2012 Member Level: Silver Points : 3 (Rs 2) Voting Score: 0|
First of all you need to know the meaning of the term conventional in conventional current.
Convention is basically an assumption.
It doesn't have any scientific reason associated with it. Same is the case with conventional current, we have to define the direction of current flow so we assumed that it flows in the direction opposite to that of electrons. We did so because otherwise some one would solve a question by taking one direction and the other will solve it by taking other direction which would be misleading. So to encounter such kind of situations we introduced conventional current.
|Author: MetalHead 18 Jul 2012 Member Level: Silver Points : 3 (Rs 2) Voting Score: 0|
I totally agree with Krypt. As a matter of fact an electric current can flow in both or either direction. The theory of conventional current was put forward just to avoid the confusion. It was assumed that since electrons that have a negative charge flowed from negative to positive, there is a positive charge flowing from positive to negative and this positive charge is called as a conventional current. It was Benjamin Franklin, who thought that the electric current was some kind of fluid that flowed from positive to negative terminals similar to the flow of fluid from high pressure to low pressure. He was the one who came up with the idea of positive and negative. Before that it was believed that the flow of electric current was a flow of two kinds of electric fluids called as resinous and vitreous. It was Benjamin Franklin who proposed that there were no two fluids but one.
This is just a theory and it has no scientific proof.
|Author: Vikram Narang 19 Jul 2012 Member Level: Gold Points : 4 (Rs 3) Voting Score: 0|
Current is defined as the charge flowing per unit time. It is constituted by the flow of positive charge. Current is always in the direction of positive charges which are called holes.
A wire consists of a large number of negatively charged particles and positively charged particles called holes.
Consider a piece of wire having reistance R connected with battery. The direction of current will be from the positve terminal of the battery to the negative terminal while the flow of electrons is from negative to positive.
As potential difference is applied across the wire the electron get drifted to the higher potential side, that is positive terminal of the battery and the positive charges (holes) moves to the low potential side that is the negative terminal of the battery. The direction of current is same as the direction of the flow of holes that is from the positve terminal to the negative terminal.
|Author: Rakesh Prakash 21 Jul 2012 Member Level: Silver Points : 3 (Rs 2) Voting Score: 0|
Current is defined as rate of flow of charge.
Charge is of two kinds. There are positive charges and there are negative charges.
By convention we take direction of flow of positive charges as positive and those of negative charges as negative.
Current is defined as rate of flow of charge.
In differential form it is defined as:
dI = dQ/dT
dI - differential current
dQ - differential charge
dT - time duration considered
here charge is generally of electrons, which is negative, hence the direction of current is opposite to that of direction of motion of electrons.
|Author: Ashadul Halder 26 Jul 2012 Member Level: Bronze Points : 1 (Rs 1) Voting Score: 0|
Electrons flow from negetive to possitive. But the charge is negetive. So the flow of current is possitive to negetive.
|Author: Ajay Kumar Jajoo 29 Jul 2012 Member Level: Silver Points : 2 (Rs 2) Voting Score: 0|
Current is defined as the charge flowing per unit time. It is constituted by the flow of positive charge.
Earlier electrons were not discovered. So current direction was taken to be the direction of the positive charges. When later electrons were discovered, it was found that the movement of electrons is in a direction opposite to that of the then defined current direction.
This is the reason why the direction of the conventional current is opposite to that of the flow of electrons.
|Author: vineet pandey 20 Aug 2012 Member Level: Bronze Points : 2 (Rs 2) Voting Score: 0|
Current was discovered before the discovery of electrons.
As we know that current is rate of flow of charge that is
so it was assumed that the charge flowing is positive.
But the erlier discovered current was named as coventional current after the discovery of subatomic particle electron.
Since flowing electron constitutes current,the direction is taken opposite to the flow due to the convention.
|Author: krishnaraj jadav 29 Aug 2012 Member Level: Gold Points : 6 (Rs 4) Voting Score: 0|
Your question is very logical that we know that the current is due to the flow of electrons then why we are taking the conventional current direction in all our study.
The main thing is that when we don't know about the current is due to the flow of the electrons at that time we assume that it is due to positive charge.
So,we assume the direction of current in wrong direction from the actual direction of flow of electrons as shown in the attached picture.
The problem is that if now we change the direction of current form conventional to non conventional then the all the theorems,law's of electrical should be changed so for this we are still using conventional current direction.
|Author: shantanu kapote 03 Sep 2012 Member Level: Silver Points : 3 (Rs 2) Voting Score: 0|
According to the theory of electronics:
As the electrons are negatively charged particles, it is natural for them to get attracted towards the positive charge, thus generating current in the circuit. Generally in many reference books we see the author has assumed the direction of current flow as
positive terminal --> negative terminal , which is just an assumption made before the puforth of real theory of the electrons. As the scientists stated it as conventional direction of flow of current , it is still in practice, to follow their law and rules. Conventional direction is universally accepted direction and is used in theory.