Question 744: Electrostats & Capacitance

Question

27 identical drops are charged at 22V each. They combine to form a bigger drop. The potential of the bigger drop will be _____________ V.

Accepted Answer

Let the charge on one drop is q and its radius is r.
So for one drop $$V = {{kq} \over r}$$
For 27 drops merged new charge will be Q = 27 q and new radius is R = 3r
So new potential is
$$V' = {{kQ} \over R} = 9{{kq} \over r} = 9 	imes 22$$ V
= 198 V

Electrostats & Capacitance

27 identical drops are charged at 22V each. They combine to form a bigger drop. The potential of the bigger drop will be _____________ V.

Choose the correct answer: