What Is Electric Current? What is the direction of current? & How the current flow in a wire?

 What is Current?

An electric current is the stream of charged particles, such as electron or ions, moving through an electric conductor or space under the influence of force.

It is measured as the rate of flow of electric charge moving through an electric conductor or space. The moving particles are called charge carriers, which may be one of several types of particles, depending on the conductor. In electric circuit the charge carriers are electron following through a wire. In semiconductor they can be electrons or holes. In an electrolyte the charge carriers are ions, while in plasma, an ionized gas, electric current is formed by both electrons and ions.

The conventional symbol of electric current is “I “& the SI Unit of Current is A “Ampere” (A). A current of 1 ampere means that 1 coulomb of electron (i.e. 6.25 x  10¹⁸ 

electron )moving through a conductor.

A= Ampere, For a large amount of current (1.000)

mA= Milli amperes, a thousandth of an ampere (0.001)

µA = micro amperes, millionth of an amp (0.0000001)

According to conventional definition of current, I = q/t, Where I is Electric current, Q is charge and t is total time taken to flow of Q charge.

Direction of Electric current:

The conventional direction of electric current is from +ve terminal to -ve terminal of a battery/Shell through the outer circuit. But the actual direction of the electron in a circuit is from -ve terminal to +ve terminal.

Figure 1.1

How the current flow in the wire?

As we know there are 3 states of matter i.e. Solid, Liquid & Gas. Every matter is composed of molecules and molecules are made of atoms. We also know inside of atom is electron, Proton & neutron. P⁺ & n⁺ are inside of nucleus and e^- travels in a circular orbit around the nucleus. All atoms are eager to become octet in which the total no. of electron in the outermost orbit is equals to 8 and becomes stable. If the number of electron present in the outermost orbit is not 8 then the atoms are not stable and electrons are called free electron.

Now let us example of copper atom, the atomic number of Cu atom is 29 it means there are 29 P⁺ & 29 e^- present in Cu atoms. These 29 P^{+ are} get accumulated inside the nucleus and e^- will get arranged around the nucleus according to 2n² formula, i.e. 1s²2s²2p⁶3s²3p⁶3d¹⁰4s¹. Here we can see there is only one electron in the outermost orbit ant it is away from the nucleus as compared to other electron therefor it is having less force of attraction. Resulting the nucleus will detach this electron very easily from the atom. Hence this electron is called free electron.

Figure 1.2

As we know in a cu conductor there a billion of atoms present and there for billion of free electrons present inside it. These free electrons revolving around the nucleus of each atoms so these e^- are moving in random direction of each other (Figure 1.2).

Figure 1.3

 When we connect copper conductor with a batter/Shell through a wire and give external force/Voltage (Figure-1.3). These free electrons detached from the nucleus and starts moving towards the positive terminal of the battery. Resulting, the convention current starts following towards negative terminal; of the battery.

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