About 2500 years ago a famous Greek philosopher Thales of Miletus observed that a material named Amber when rubbed with wool or cat’s skin acquires the property of attracting light bodies like small bits of paper, straw etc. In 1600 AD, Dr. William Gilbert, physician of Queen Elizabeth of England discovered that the property of attraction was limited not only to Amber, but there are several other materials such as glass, ebonite etc. which acquire the property of attracting light bodies on being rubbed with some other material. On acquiring this property of attraction the material is said to be electrified and the mysterious cause due to which this property is developed is called Electricity. This name was given by Thomus Brown in 1646 AD. Since this property in materials is developed due to rubbing i.e. , by friction, hence the electricity developed by this method is called frictional electricity. It is also called, ‘Static Electricity’ because the charge thus developed does not flow from one point to the other but remains stationary on the two bodies which are rubbed against each other. On being electrified the body is said to have acquired electric charge. Hence an electrified body is also called charged body.
In Greek language Amber is known as electrum and this is the root of all words like electric charge, electricity and finally electron.
Basic To Advance lable Info for All exams
* Electrostatics- It is that branch of physics in which we study about static electricity.
* Static Electricity- When two body of diffrent material are rubbed together< they become charged or electricfied due to transfer of electrons from one body to another body. The charge devloped on body is called static electricity.
* charge- When two bodies are rubbed together and after rubbing, when they are taken near light objects, they attract light objects. The property by which body attract light objects is called charge.
SI unit of Charge is Ampear, which is called columb.Columb is a big unit of charge. so, Charge is generally expressed in ” mc, hc, nc and pc “.
mc= milli columb = 10 to the power -3
hc= micro columb = 10 to the power-6
nc= nano columb = 10 to the power-9
pc= pico columb = 10 to the power-12
* Kinds Of charges- Atoms of all elements are basically natural each atom contains equal number of negatively charged partical electrom and positively charged particals proton.
When electron are transferd from one body to another body, Both body becomes charge. The body which gains electron becomes negatively charge and the body which losses electron becomes positively charge. So, There are two kinds of charges
1: Positive charge
2: Negative Charge
* Quantisation Of Charge- Electrons can be only transferd in whole numberFrom one body to another body. So, Magnitude of charge devlope in body is always equal to integral muntiple of “e”.
This is called quantisation of charge. If number of electrons transferd from one body to another body is “n” then magnitude of charge devloped on each body,
* Additively Of charge- Charge is a Scaler quantity, So cgarge is added according to rules of algebra.
If +Q1, -Q2, +Q3 and -Q4 are four charges, then net charge is
* Principle of conservation of Charge- Charge can neighter be created nor be destriod. It can be only transferd from one body to another body.
Net charge of isolated system is to be always conserved. As per example, When two bodies of diffrent matterial are rubbed together, Then one body becomes positively charge and another body becomes negatively charged. Magnitude of charge on both bodies is to be same, So net charge of bodies is equal to zero, before rubbing net charge of both body is also=0 which conforms that net charge of isoleted system is to be conserved.
* Continous Distrubition Of Charge ( Conductor or insulator )- Thoser material in which free electron are present are called conductor and those material in which free electron are not present are called insulator.
When charge is supplied to a conductor, It is disturbted in whole part of conductor since atoms of conductor are very very close. So, charge distrution is assumed contionous.