Question

How can we know that , an object is having a'' positive charge" or " negative charge"??
How ca we measure it ??

Answer 1

In order to tell the sign of an object charge, you need another object with a known positive or negative charge.If an unknown charge is attracted by a known positive charge,then we can say that the unknown charge is a negative chatge.If the positive charge repels the unknown charge then it is a posive charge

Just like that if we are using a known negative charge

Point is that same charges repel and oposit charges attract

There is a device called Electro meter is used to measure the charge