[Physics Class Notes] on Electric Current in Conductors Pdf for Exam

Electric current is the flow of electrons through a conductor. The movement of these charged particles creates a voltage or electrical potential difference between two points in a circuit. This potential difference can be harnessed to power electronic devices and appliances. In order to study electric current in conductors, it is important to understand how these electrons move and what factors affect their flow. By understanding the basics of electricity, you can more effectively learn about electric current in conductors and how to apply it in your own life.

Effect on the Flow of Electrons

There are several things that affect the flow of electrons through a conductor. The most obvious factor is the amount of current flowing through the circuit. This is measured in ampere (A) and can be affected by the resistance of the material as well as the number and size of the conductors. The resistance of a material is determined by its resistivity, which is a measure of how difficult it is for electrons to move through the substance. A higher resistivity means that there will be more resistance to the flow of current and vice versa.

What is Current?

When we apply a potential difference across any material, a flow of electrons (charges) takes place. The rate of flow of this electron is called current. If the material on which the potential difference is applied is a conductor, then we say this current to be the current in the conductor. If Q amount of charge flows through any cross-section of a conductor in time t, then- the current is defined as the rate of the flow of electrons, i.e

[I = frac{Q}{t}]

The SI unit of the current is Ampere (A).

The current is mostly divided into two groups, i.e. alternating current and direct current, depending on the electric charge flow. In direct current, the charges flow through unidirectional while the charges flow in both directions in alternating current.

The Direction of the Current

As per the electron theory, when the potential difference is applied across any conductor in a circuit, some matter flows into it that actually constitutes the flow of current. It is believed that the matter flows from a high potential to a lower potential, i.e from the positive terminal to the negative terminal of the battery. Since the current has the direction, so technically, it should be a vector quantity because it has both the direction and value but in reality, it is a scalar quantity. 

()

 

Thus, conventionally the direction of current flow is from the positive terminal to the negative terminal of the battery.  

Current in the Conductor

We all know that conductors are the substances that allow current to pass through them. When the conductor is not connected to the battery, the free electrons tend to move freely here and there. This electron moves randomly inside the conductor with a certain velocity. This velocity is called thermal velocity. Since the whole motion is random, the average velocity equals zero. 

Next, the external electric field is applied. Once the battery is applied to the conductor, the electron starts moving towards the positive terminal of the battery. As the electrons move towards the positive terminal of the battery, it gets accelerated.  Since the electron is moving in only one direction, it gets collides with the positive ions as well. With this collision, electrons tend to lose the velocity which they had gained because of the acceleration. Whenever any charged particle goes into any conductor, it doesn’t move into a straight line, it collides with the other charged particle. Because of this loss, a very small increase in velocity takes place. The average of this small gain in the velocity is called the Drift velocity. Drift velocity can be defined as the average of the velocity gained in a material due to an electric field.

[V = frac{I}{nAq}]

Where,

v – Drift velocity

I – Electric current

n – no of electrons

A – Area of the cross-section of the conductor

q – charge of an electron in coulombs

Mobility of an Electron

The mobility of an electron is defined as the drift velocity of an electron for a unit electric field. The mobility depends upon the potential difference applied, conductor length, the density of charge carriers, current and area of the cross-section of the conductor. 

[mu = frac{V_{d}}{E}]

Where, μ = mobility of an electron

V_d = Drift velocity of an electron

  E =  Electric field applied

Importance of Electric Current in a Conductor

The electric current in a conductor is important because of multiple reasons:

1. It is the means by which electronic devices and appliances are powered.

2. Without electric current, we would be unable to use many of the devices that we take for granted in our everyday lives. From computers and smartphones to televisions and refrigerators, all of these appliances require an electrical current in order to function. By understanding how electricity works, you can better utilize these devices and make your life a little bit easier.

3. Electricity is also responsible for powering many industrial applications. Factories use large motors to run their machinery, and these motors require a steady supply of electrical current. If there was no electric current in conductors, our world would look very different indeed.