Question
Tue April 14, 2015 By: Sujay Sarkar

Why do similar charges repel and opposite charges attract? Explain the concept using a suitable example.

Expert Reply
Romal Bhansali
Wed April 15, 2015
Take two glass rods rubbed with silk cloth. Suspend one glass rod using a silk thread on to a stand and bring the other glass rod near it. We see that both the glass rods repel each other. Both the glass rods are rubbed with same silk cloth, and hence have same charges on them. This shows that like charges repel each other.
 

Now, take two ebonite rods rubbed with fur. Suspend one ebonite rod using a silk thread on to a stand and bring the other rod near to it. We see that both the ebonite rods repel each other. Both the ebonite rods are rubbed with same fur, and hence have same charges on them. This also shows that like charges repel each other.

Now, a glass rod rubbed with silk is suspended with a silk thread on to a stand. Take an ebonite rod rubbed with fur near to the suspended glass rod. It is seen that both the rods attract each other. Since, both the rods are rubbed with different cloths and attract each other, different charges are developed on them. This shows that unlike charges attract each other.

 

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