What is an electric charge? Is it a scalar or vector quantity? Give SI unit and dimensional formula of electric charge.
Electric charge: Electric charge is the characteristic of a body or object that causes it to experience an electrical force when placed near other body or object.
When two substances are rubbed against each other, there can be exchange of electric charge. The process by which a substance or an object acquires electric charge is called electrification.
The electric charge on an object can be measured and hence electric charge is a physical quantity.
Electric charge is a scalar quantity.
SI derived unit of charge is coulomb and denoted by C.
Dimensional formula of charge:
Electric charge, $q = It$, where I is electric current and t is time.
$\therefore$ Dimensional formula of electric charge = [AT],
where A = ampere, symbol of SI unit of electric current.
Kinds of Charges :
Electric charges are of two types: positive electric charge and negative electric charge}. The choice of these names i.e. positive or negative is simply because of a convention. It was Benjamin Franklin, a great American physicist, who called the charge on a glass rod rubbed with amber as positive charge and the charge on amber as negative charge. This convention of calling the charges as positive and negative is universally followed.
Positive charge is denoted by a (+) sign and negative charge by a (-) sign. In early days, charge developed on glass i.e. positive charge and charge developed on amber i.e. negative charge.
Neutral object: The object having no net charge (i.e., having equal number of positive and negative charges) is called neutral object.