Have you ever seen sudden sparks of light in the sky during thunderstorm and rain?
Isn’t it terrifying & interesting at the same time?
Lightening is electricity, but in natural form. You cannot use it to light the bulb in your house because it’s very powerful. Lightening strike causes fires. You might have heard about death of people during a thunderstorm.
How does a bulb in your house lights up then?
A Light Bulb
It lights up because of the electricity which is made for human use. It is less powerful and can be easily used to power lights, fan, washing machine and other appliances in our house.
Power lines that carry electricity
You need : A plastic ruler, dry human hair, tiny bits of paper.
Step 1: Lay down the tiny bits of paper on your table.
Step 2: Rub the plastic ruler vigorously on your dry hair.
Step 3: Bring the ruler close to the tiny pieces of paper.
Can you see some magic? Well that is how electricity was discovered!
The scale starts picking up pieces of paper from a distance.
Paper pieces being picked up by a charged ruler
Electricity was discovered between 624 B.C. to 546 B.C. by a greek philosopher Thales of Miletus. Instead of a rubbing the plastic ruler against dry hair, he rubbed a material called amber with fur.
Then he discovered that when this amber brought near to straw, it could pick up small pieces of straw.
Thales of Miletus
2,200 years later William Gilbert and Robert William Boyle started experimenting and explaining about electricity.
Atoms and Electrons
To understand why a ruler rubbed on dry hair attracts pieces of paper, we first need to look at the fundamental unit of matter, atoms.
Take a chalk piece and try breaking it into small pieces. Keep breaking it until you can break it further into small pieces.
You will reach a point where you can no longer break it into smaller pieces. Similarly, any material that we see in nature can be broken down, up to a limit. After that you cannot divide it further because you reached at the smallest unit of matter i.e. atom.
You must be thinking, why?
The reason is atoms are indivisible(cannot be divided) and everything in nature is made up of atoms. They are the smallest particles that make up everything that we can see around us. However, different types of materials are made up of different atoms but we cannot see those atoms because they are very very small.
Copper Coin and its atoms
Although an atom cannot be divided or broken further but inside atom there exists three types of particles: protons, neutrons and electrons.
Atom is ‘electrically neutral’. Normally, atoms have equal number of protons and electrons.
When electrons are in excess then that substance is called negatively charged. When protons are in excess, it is said to be positively charged. You can measure it like mass.
Protons are in excess, when an electron leaves an atom, making the atom positively charged. When an electron enters an atom, atom becomes negatively charged. Everything around us has some charge.
Whenever atom becomes charged due to electrons coming into it or going outside it. It tries to go back to its natural form which was being neutral.
Opposites attract and similar repel
What is electricity
Electricity is defined as the ‘flow of charge’. And primarily it is the flow of negative charge or electrons.
In order to create electricity, electrons need to become free from their atoms. In some materials electrons are loosely attached with the atoms and can easily leave it. The movement of electrons gives us electricity, which we can use to make our life easier.
Electrons arrangement in a copper atom
Such materials are more suitable for carrying electricity. Copper is one such material which is extensively used in all the wires.
Types of electricity
Electricity exists in our world in two forms-
a. Static electricity
b. Current electricity
We will discuss about both one by one.
a. Static electricity
Static electricity is the build-up of charge in materials. Static electricity often occurs when you rub things together.
Materials are made of atoms that are normally electrically neutral because they contain equal numbers of positive charges and negative charges.
When two materials are in contact, electrons may move from one material to the other, which leaves an excess of positive charge on one material, and an equal negative charge on the other. When the materials are separated they retain this charge imbalance.
By rubbing, opposite charges build up on two different objects.Whenever these charges find a path to move, a static discharge occurs to balance the charges in those objects.
Let us go back to the activity where you discovered electricity, by picking paper bits using a ruler.
When you rub plastic scale with your hair, electrons get transferred from your hair to the scale. Ruler now holds these electrons and is negatively charged. The bits of paper do not have any net charge. Now when you bring a negatively charged object close to paper bits, it attracts the positive charge of the paper.
Let us look at another activity where you can see the discharge as spark.
Sit on any plastic chair and rub your clothes against it. When you do this, charge develops on your clothes. Now, touch any metal. You will see a spark.
This happens because of static electricity. When you sit on a plastic chair, electrons get transferred from your clothes to chair. Now, you are positively charged and chair is negatively charged. When you get up from your chair, you take that charge with you.
When you touch any metal, electrons from the metal flow to you to balance your positive charge. You can notice a small air gap between you and the metal. The electrons flow through that air gap also. These electrons collide and excite the electrons in air. These excited electrons release energy in the form of light which you see as a spark
b. Current Electricity
Current electricity is due to the movement of electrons. In static electricity, charges gather and remain at rest and only flow when they find any path. In current electricity, charges always keep moving.
Notice how electrons keep flowing throughout this path.
This type of electricity is used to do many things, like, to light a bulb, to turn a fan, to run a washing machine etc.
Electricity is very useful but it can be dangerous also. If you play with electricity, you can even die.
Here are some tips which you can follow to stay away from the dangers of electricity:
- Don’t play with household power sockets or push things into them.
- Always follow the instructions on electrical equipment and ask your parents for help if you don’t understand.
- When you unplug something from the wall socket, don’t pull the cord, use the plug.
- Don’t spill water on electronic and electrical items, especially if they are plugged in.
- Don’t place items on top of electrical cords. The cords could get damaged and cause a fire.
Some interesting facts
- Electricity travels at the speed of light – more than 186,000 miles per second!
- A spark of static electricity can measure up to three thousand (3,000) volts.
- A bolt of lightning can measure up to three million (3,000,000) volts, and it lasts less than one second!
- Electricity always tries to find the easiest path to the ground.
- Electricity can be made from wind, water, the sun and even animal poop.
- A 600 megawatt natural gas plant can power 220,000 homes.
- The first power plant – owned by Thomas Edison – opened in New York City in 1882.
- Thomas Edison invented more than 2,000 new products, including almost everything needed for us to use electricity in our homes: switches, fuses, sockets and meters.
Benjamin Franklin didn’t discover electricity, but he did prove that lightning is a form of electrical energy.