Electric Charge and its Properties

1. Electric charge(Q) is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. 

2. The additional property of Protons & Electrons, which gives rise to electric force between them, is called Electric Charge.

3. According to William Gilbert, Charge is something possessed by material objects that makes it possible for them to exert electrical force and respond to electrical force.

4. Electric Charge is a Scalar Quantity. Its SI unit is Coulomb(C).

5. One coulomb is the quantity of charge transferred in one second, i.e., Q=I×t , where Q is the electric charge, I is the electric current and t is the time.

6. There are two types of charges:

1. Positive Charge(+): Positive charge is produced by the removal of electrons from a neutral body. That is, positive charge means deficiency of electrons.

2. Negative Charge(-): Negative charge is produced by giving electrons to a neutral body. That is, negative charge means excess of electrons on a neutral body.

   
   

Properties of Electric Charge

1. Conservation of Charge: The charge of an isolated system remains constant. This means that charge can neither be created nor destroyed, but it may simply be transferred from one body to another.
   Eg. When a glass rod is rubbed with silk, the glass rod becomes positively charged and the silk becomes negatively charged. The amount of positive charge present on the glass rod is found to be exactly the same as negative charge on silk. Thus, the system of glass rod and silk, which had zero net charge before rubbing, still possesses zero net charge after rubbing. 

2. Quantisation of Charge: The charge on any body can be expressed as an integral multiple of fundamental charge, charge on one electron (e)
   q=±ne , where n is an integer positive or negative and e is the basic unit of charge.

1. The magnitude of charge on a proton or an electron(e=1.602192×10–19C) is called elementary charge.

2. Quantisation of Charge can only be observed at microscopic level.

3. Quantisation of Charge is also known as discrete nature of charge.

3. Additive nature of charge : Total charge on an isolated system is equal to the algebraic sum of charges on individual bodies of the system.
   If q1 ,q2 , q3 ,.... Are electric charges present on different parts of an object, then the total electric charge present on the object,  q= q1+ q2 + q3+......

4. Charge is unaffected by motion: The charge on a body remains unaffected of its velocity, i.e.,  
   Charge at rest = Charge in motion

5. Like charges repel while unlike charges attract each other.