To understand electricity firstly we have to understand atom (which is the smallest particle of any matter). Atoms are composed of nucleus and revolving elections, nucleus is compost of positively charged particle which present at the center of an atom and electrons are negatively charged particles which orbit the nucleus. The number of proton inside an atom determines which element it will be. Even we know this fact, whenever we can create only few atoms in laboratory by bombarding alpha particles on nucles of atom. Electrons are bounded in their orbit due to the attraction of nucleus which is located centrally in an atom, as we know like charge repel and unlike charge attract, that is why electrons orbiting the nucleus. But the electrons which is present in the outer orbit or shell of atom can become free of their orbit, due to some external force. The electrons which become freed from orbit is known as 'free electrons', which move from one atom to another.
On the basis of electron holding capacity, materials are classified into two types.
I. Conductor- which allows huge amount of electrons to move freely.
II. Insulator- which allows very few (negligible) amount of electrons to move freely.
So, now we know that all the matter in this universe are made up of atom, and atoms are made up of electric charges. Therefore, they have electric charges. Here a question arise.
- If every matter have protons and electrons in it, then why they did not work like a magnet or any electric source?
Answer- For the matter that has a balanced number of electrons and protons are refer as neutral, means the force of electrons and protons are balanced with each other.
Example: Hydrogen(H) have 1 Proton and 1 Electron.
-(1×1.6×10^-19)c on electron and
1×1.6×10^-19c on proton
Here is an example which satisfy every matter are made up of electrons and protons.
Do you know, What is static electricity?
Electricity which does not flow is know as 'static electricity'. When you rub two materials with each other then those materials will loose electrons from their outer edge and will poses static electricity on their outer edge. One material will work like south pole of a magnet and another like north pole. When we rub two materials with each other, then the electrons of one material move forcefully into the next material, as it cause decreasement in electrons of one material. And now the electrons of the one material is lesser than proton, so its force becomes imbalanced and at the same time another material have much electrons than protons. So there is also an imbalance of force. That is why, it starts acting like a magnet. You can do this experiment with a scale, your hairs and some small pieces of papers. I think there is no need to tell you the steps of this experiment, because I know you are so smart.
Now comes to flowing electric current
The flow of electrons from one matter to another is termed as electric current. And the characteristics of electric current is totally differ from static electricity.
How electricity flow?
We use wires which is made up of different metals to conduct electricity. Atoms of metals are mede up of free electrons which can easily move from one atom to another. When we connect wire to make a simple circuit then wire gets electrons from power supply point, (battery or other source) then atoms of the wire becomes imbalanced and to make it balance again, wire have to transfer those electrons to consumption point (ie. Any electric or electronic appliances). In this way electrons move and electricity flows.
- Current is the flow of electrons but, current flows in opposite direction of electrons.
- Electrons flows from negative to positive whereas current flows from positive to negative.
- Current is determined by the rate of flow of electrons through a cross-section area of a conductor per second. Current is measure in 'Ampere' (symbol-'A').
- A current of one ampere can define as the amount of charge flowing through the cross-section area of a conductor per second. Or it can be written as
I(current) = Q(charge)/t(time)
Voltage
Voltage is the force which required to make current flow through a conductor. It is also known as 'Potrntial'. So, voltage is a potential which makes current to flow from high potential to low potential. For example, suppose that an element has more positive charges, so it has higher potential whereas the second element has more negative charges, so it has low potential. The difference between two potential is termed as 'Potential Difference' The SI unit of Voltage (PD) is 'Volt' ('V'). One volt means a force which makes current of one ampere to move through a conductor when the resistance is one ohm (SI unit of resistance) throughout the conductor.
What is resistance?
Resistance is a natural properties of a conductor which restrict (partially stop) the current to pass through it. Resistance increase with increasement in length of conductor (ie. Wire) and decrease with increasement in cross-section area of conductor. The SI unit of resistance is 'Ohm' which denoted by the greek letter 'Omega'. The resistance of one ohm means the conductor allow current of one ampere when the given PD (voltage) is one volt. The resistance of any material depends up on two basis:
1. Natural resistance
2. Temperature
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