1.3 Electrical Interactions 2
Well, considering these observations, we observe that something is happening after the rubbing process. After the rubbing process, these objects are generating forces to one another, and in one case, the force is an attractive nature. And in the other case, it is a repulsive nature.
To be able to differ these two natures from one another, physicists introduced the concept of positive and negative charge. And they defined the charge associated with the plastic after it is being rubbed with wool as negative charge. And charge associated with glass after it is being rubbed with silk cloth as positive charge.
From these two cases, then, we can see that when the objects are likely charged, namely negative and negative or positive and positive, the nature of the force that they exert to one another is a repulsive one. In other words, they repel one another.
On the other hand, when we compare the glass which is rubbed with silk cloth, therefore positively charged and plastic pendulum, which is rubbed with wool cloth, therefore negatively charged, then the nature of the force that they exert to one another is an attractive nature. In other words, these two objects attract one another.