Electric Currents in Conductors

 

Electrical Conductors are a very important part of our lives. Our entire power grid is made up of electrical conductors and insulators. Recently we’ve added another term, ‘semiconductors’ to this list! How does electric conduction work? What happens when an electrical conductor conducts electricity?

Understanding Electric Current:

In the previous article, we understood how the movement of an electron creates an electric current. Imagine a body, invariably made up of atoms. The atoms are made of electrons, protons and neutrons. Due to being loosely connected, electrons are able to move freely inside the body, which is called electrical current. Under normal condition, the electrons are moving randomly inside the body and hence the net electric current is zero since they all cancel each other out.

The application of an electric field around the body is also another way to cause movement in electrons but the catch is that the electric field does not influence everything. This is where the distinction between electrical conductors and insulators comes in electricity. The electric field can cause the electrons to move around. Through this influence on electrons, we can give a net direction to the motion of the electrons. This is how we generate an electric current.

Visualizing Electric Current:

Electric Current

Imagine a circular rod made of an electrically conducting material. Apply an electric field of magnitude Q to it. This means that one end of the rods assumes a positive potential and one a negative potential. Since electrons are more mobile than protons, they rush to cancel out the positive potential developed at the left end of the rod. This motion of electrons is also called an electric current. According to scientific convention, electric current flows opposite to the direction of the flow of electrons.

Conductors:

Bodies in which the application of an electric field results in the generation of an electric current due to the movement of the electrons is called an Electrical Conductor. In such bodies, the electrons are free to move around inside the body and their random motion can be influenced by an electric field. Most electrical conductors are metals mainly because metals possess electrons in the outermost orbit where they are most loosely held and can move around easily. The wires supplying electricity to your houses are supplying fresh energetic electrons to your house for you to use. We have learn’t to use it and we have become completely dependent on electricity.

Insulators:

Certain bodies do not possess free moving electrons like metals. Materials with fixed electrons such as plastics and rubber do not respond to the electric field at all. The electrons in such materials is not free to move around and generate an electric current. Such bodies are called Electrical Insulators. The plastic coating around the wire is an insulating material which prevents you from getting shocked by the electricity in the wire within.

Electricity is vital to our lives. We may build our machines but electricity is what runs it.

Stay tuned with byju’s to learn more about conductors, insulators and many more.


Practise This Question

A physicist is investigating the effect that different conditions have on the force of friction. The material used is an ordinary brick, with a mass of 1.8 kg. It is pulled across the surface of a wooden table. Friction is measured by pulling the brick with a string attached to a spring scale, calibrated in newtons (N). When the brick is pulled at constant speed, the reading on the scale is equal to the force of friction between the brick and the table top.
Experiment 1:  The brick is placed on the table in three different positions. First, it is allowed to rest on its broad face (area =180 cm2), then on its side (area =130 cm2), and finally on its end (area =56 cm2)
Table 1
Area (cm2)18013056Friction (N)7.17.37.2

Experiment 2:  A wooden block of mass 0.6 kg is made to the same dimensions as the brick, and the experiment is repeated.
Table 2
Area (cm2)18013056Friction (N)1.21.11.2

Experiment 3: The time, the wooden block is loaded by adding 1.2 kg of extra mass on top of it, to give it the same weight as the brick.
Table 3
Area (cm2)18013056Friction (N)3.53.63.7
From Experiment 1, it would be reasonable to hypothesize that: