Explanation of charge for a student just entering physics

Question

I am trying to understand charge what it is actually and how electrons have negative charge like suppose I assume that scientist assume protons have something because of which they behave like that (attract other electrons and repel other protons) but what do they mean by electron have negative of that thing.how can something have negative of a thing.

Answer 1

One should first remember that this is largely conventional and very convenient.

When discussing the force between charges, what one wants out of these assignments is to get the same qualitative behaviour for two like charges, and a different qualitative behaviour for different charges, and giving a algebraic sign to charges does just this because the product of two negative numbers is positive, the product of two positive numbers is positive, but the product of one positive and one negative number is negative.

It is also convenient because we often need to compute the net amount of charge on an object, and we know how to add positive and negative numbers.

As far as Coulomb’s law goes, another way to handle the repulsive or attractive nature of the interaction could have been as follows: assign the number 0 to one type of charge, the number 1 to the other type. When you bring them close together they attract if the sum of their “number” is odd, and repel if it is even. This rule would not work if you need to add the charges, such as a situation where a type 0 charge would be made close to another object containing a number of charges of type 1 and type 0.

So it’s not so much that the electron charge is negative and the charge of the proton is positive (indeed the assignment of the algebraic sign could have been reversed without problem provided everything other assignment of the algebraic sign was also reversed), but it’s that these charges are of different types, and that assigning a positive or negative value to these makes it easy to algebraically add or multiply the signed quantities when needed.

Answer 2

If you rub two objects together you find that after being rubbed some objects attract one another and others repel one another.
Benjamin Franklin used what is called a "single fluid model" whereby rubbing either increases the amount of fluid in a body by fluid being transferred from the object doing the rubbing to the object being rubbed or conversely the rubbed object had less fluid by the transference of fluid.
If an object had more fluid it was called positively charged and an object with less fluid was negatively charged and these are terms that Franklin introduced.

It was surmised that if two objects with an excess or a deficit of fluid repelled one another (like charges repel) and an object with an excess of fluid attracted an object with a deficit of fluid (opposite charges attract).

We now believe that it is electric charges (electrons) which are transferred from one object to another during the rubbing process.