# Introduction to electricity

Have you ever thought, What makes your room’s lights turn on? Why do you press that switch button to turn on the torch light? They occur because in the form of electrical energy there is energy flow. There is and can be experienced in many ways and amounts of electrical energy. For instance, when you touch a metal portion of your TV, you may feel a small shocks, or you may feel a shock when you touch laundry clothes. There may also be electricity in lightning bolts. Let’s first learn where and how it all comes together to comprehend this very powerful thing.
 Electricity

## What is electricity?

There is electricity due to some activity of nature’s smallest particle called the atom. The atom is matter’s basic building block. An atom is so tiny that it is not visible to human eyes. Only with the help of very powerful magnification devices (we call it electron microscope) we see them.

Below is an illustration of an atom:

Structure of the atom showing neutrons protons and electrons:
 Structure of the atom

There are three subatomic particles in the atom — Protons, Neutrons, and Electrons. Protons and neutrons are right in the atom’s nucleus (i.e. center or core). There are electrons around the nucleus that are constantly moving very fast. Because they have some energy, the electrons can migrate from one atom to another atom.

Neutrons are charge less. Protons are being charged positively. Electrons are charged negatively and surround the nucleus. Electrons encircle the nucleus because opposite charges are attracted to each other (negative charging electrons and positive charging protons) and charges tend to move away from each other.
 Transfer of electron

The electrons can move from one atom to the other and this leads to the electricity production

In simple terms, electricity is the flow of electrons.

There are two types of electricity:
1. Static electricity
2. Current electricity

Here we will discuss in details about Current electricity.

## What is current electricity?

Electric current in simple terms are electrons in motion along a path, regardless of the number of electrons flowing A conductor like copper, silver and aluminum can be the route. Free electrons may be compelled to migrate from one conductive region to another.

• Current:

Current is the rate of flow of an electrical charge through a conductor. It is the number of electrons in a second that passes a given point. This implies that the current is higher if more electrons pass through a specified point.

The symbol for current is the letter “I”.  Electrical current is measured in Amperes or “amps”.

• Voltage:
Voltage measures the difference in electrical energy between two points of a circuit. Voltage is measured in Volts and represented by the letter ‘V’

Here is an illustration to help you to understand the current and voltages more clearly.

Think of electrical charge, current and voltage as a huge water tank connected to a pipe as shown in the figure below:

 Simple Illustration of current and voltage

Here the tank can be considered as the source of charge (i.e. battery) and water inside the tank represents electric charge. The more water inside there, the more is the charge. Voltage is just like pressure. The more the water, the higher the pressure (voltage) at the end of the pipe.

In the diagram above, there is voltage at point A, but no current, because the tap is closed and the water is NOT flowing (means the charge is not flowing through the pipe i.e. the conductor). This implies that there may be voltage without current, but no current without voltage.

And at the point B, the tap is opened and water flows (means the charge is allowed to flow). At this point, there is both voltage and current because there is a certain amount of flow.

If we open the tap to drain some water out, the pressure will reduce (in other words if charge is allowed to flow continuously after certain time the voltage will decrease).

• Electric Power:
Electric power is the rate, (i.e. per unit time), at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt (one joule per second).

It is calculated as,     Power = current* voltage

• Resistance:
Resistance can be defined as the disturbance of interruption in the path of current flow through the conductor. They are the power consuming device that converts electrical energy into other forms of energy that may or may not be useful to us. It is anything that gets in the way of the electricity. Examples include bulbs, lamps, and buzzers and so on. These resistors use up some of the electricity. Without them, there could be a short circuit.

• Conductor:
A conductor is a material that allows electricity to pass easily through them. There are more free electrons in the atoms of conductors, and are free to move from atom to atom. As a result, electric charges are free to move from place to place. A good conductor provides less resistance and good conductance.

Examples of good conductors:

Aluminium, copper, gold, water, etc are examples of conductors. This is why electricity producers use copper and aluminium wires to carry power from generating plants to consumers. Conductors also allow heat energy to pass through them easily.

• Insulator:

An insulator is a material that does not allow electricity to easily pass through them. The electrons in the atoms of insulators do not freely move from atom to atom. As a result, electric charges do not freely move from place to place. There is more resistance to the movement of the electrons.

Examples of good insulators:

Rubber, plastics, wood, paper, etc are all best examples of good insulators. These materials are also poor conductors of heat energy.
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