Question

Short Answers:

1) Two insulator materials are brought near each other. There is a definite repulsion between the two objects. From this, what is known about the electrical properties of the two insulators?

2)A metal rod is rubbed on the back of a dog. The rod is then brought near an electroscope.
What will happen to the leaves of the electroscope? Why?

3)When capacitors are connected in ________ the total capacitance decreases, the _______ is the same for each capacitor, and the ___________ adds.

4)Four isolated electric charges are brought near each other. If the electric potential energy is zero for the system, what is known about the polarity of the charges?

Answer 1

Ans :  

1) Since the insulators are repelling from each other, then these two insulators will have charge of same sign either both have positive charge or negative charge that is why they repel.

2) When the metal rod is rubbed on the back of dog, the metal rod gets charged. The metal rod induces charge in the leaves of electroscope by induction. Hence it will attract the leaves of electroscope.

3) When the capacitors are connected in Series , the total capacitance decreases, the Charge is the same for each capacitor. and the Voltage adds.

4) Since the electric potential energy of the system is zero, the polarity of the charges must be opposite. That is two charges must be of same sign and the other two charges must have opposite sign.