This blog discusses electric charge and the history of charge. How the Kite experiment proved What the charge is. Also, about the unit of charge.
History of electric charge
Ancient Greeks knew about static electricity around 600 BC (they discovered the attractive property of amber when rubbed).
Benjamin franklin choose the “positive” and “Negative” labels and signs for electric charge.
He could even name Tom and Jerry, and we wouldn’t even know that, But, remarkably, he used positive and negative to label them and made it more technical. There is nothing like Positive and Negative charge; it is just names of two different properties they saw in charge.
In the famous Millikan oil–drop experiment, Robert Millikan discovered a charge on 1 electron.
Kite experiment
In the 18th century, Benjamin Franklin conducted extensive research on electricity and proved that light is a form of electricity by his famous kite experiment. This experiment helped him to invent a lightning rod.
He also was the founding father of the United States of America; he invented something phenomenal, and it was like alien technology for the people of that time
Nobody must have imagined that the kite we use for fun would play a significant role in the discovery of charge.
With his son William, He flew a kite in the skies during a thunderstorm; he made a simple kite with a silk handkerchief instead of paper. He attached a pointed wire to the top of the kite as a conductor. At the bottom end of the string, he tied silk ribbon, and it was kept dry otherwise, he would get electrocuted, and to understand this, you have to read our next blog on conductors.
A metal key was fastened where the string and ribbon joined and was connected to the Leyden jar by a metal rod to accumulate electricity. Leyden jar is a device that could store an electrical charge for later use. (Leyden Jar is another name of Capacitor, you can say)
When the thunderstorm passed over the kite, the kite was not struck by lightning directly; instead, the conductor drew the electrical charge from the storm clouds to kite, and it flowed down the wet string through the metal key into the Leyden jar he was even able to collect some of the electric charges.
What the electric charge is?
Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field……blah blah blah… kill… Blah Blah…. Sorry I used the terms from Far Cry Blood Dragon.
We all have heard about this boring definition of charge.
When you remove the sweater from the body, you see a spark; in the dry season, while walking on the carpet, you experience a spark, sometimes spark produced in your computer.
Have you ever experienced such things in life? But, then, you might have to wonder why these things happen?
This little example reveals the presence of electric charge in our life. Just like “mass” is with you every time. Issac Newton discovered the gravitational force, and Charles Coulomb did something exactly with the charge; he also found the force between two charges. For Newton, Mass was his best buddy, and for Coulomb, the charge was the best buddy. Every object contains a vast amount of electric charge.
You might have to wonder if the charge is present all the time, then how come we do not experience this all the time?
The vast amount of charge in everyday life is hidden because an object contains an equal amount of positive and negative charges. Which causes the object to happen electrically neutral (has no charge)
When we say that an object is charged, it is actually in an unbalanced state. Charged objects interact by existing forces on one other.
Simple Illustration
Here, tiny amounts of charges are transferred from one end to the other making it unbalanced.
We rub the silk over the rod to increase the number of contact points, and thus some amount of charge is transferred.
If we hang this charged rod from thread and place the similarly charged glass rod near to the first one, it experiences the force of repulsion (both rods repeals each other)
Similarly, if we place a plastic rod rubbed with fur nearer to the charged glass rod, the two rods will attract each other (force of attraction).
When the glass rod is rubbed with silk, the glass loses some of its negative charges and has a small unbalanced positive charge, but when the plastic rod is rubbed with fur, it gains a slight negative charge, which attracts repeals the charges.
From the above two examples, we can conclude that,
Conclusion – Attraction happens between charges when their signs are different, and repulsion occurs when their signs are the same.
Unit of charge
Unit is used to measure the quantity.
The unit of charge is the Coulomb.
Charles Coulomb was a French scientist who studied the charge and its forces, so from his name, the SI unit of charge is the Coulomb (C).
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