Nature of force: A positively charged plastic rod is suspended by nylon string.
Now a negatively charged polythene rod is brought near it. What do you observe? The plastic rod will move towards the polythene rod. So, it is proved that two oppositely charged object attract each other. [Fig: a]
Now what will you observe when a positively charged plastic rod is brought near a freely suspended positively charged plastic rod the suspended rod will move apart quickly. That is charges of same nature repel each other. This is call Electric Force.
Coulomb’s Law: We know that the charges of opposite nature attract each other and charges of same nature repel each other. The force of attraction or repulsion between the two charges depends on,
- quantity of charges.
- distance between two charges.
- the nature of the medium between the two charges.
Scientist Coulomb states a law about the force of attraction or repulsion between the two charges. This is called Coulomb’s law.