Question

How can we know that a object is chaerged positively or negatively ??

Answer 1

In order to tell the sign of an object charge, you need another object with a known positive or negative charge. If you rub a piece of glass with silk, it will have a positive charge (by convention). If you rub a piece of amber with fur, it will have a negative charge (also by convention). Use whatever you have handy. Let's say you use a piece of glass rubbed with silk. If your object is repelled by the glass, then it has the same charge as the glass (positive). Otherwise, your object has a negative charge. hope u like it