Electrostatics Question 775

Question: The 1000 small droplets of water each of radius r and charge Q, make a big drop of spherical shape. The potential of big drop is how many times the potential of one small droplet?

Options:

A) 1

B) 10

C) 100

D) 1000

Show Answer

Answer:

Correct Answer: C

Solution:

[c] Volume of big drop=1000 $ \times $ volume of each small drop $ \frac{4}{3}\pi R^{3}=1000\times \frac{4}{3}\pi r^{3}$

$\Rightarrow R=10r $

$ \therefore V=\frac{kq}{r}\text{ and }V’=\frac{kq}{R}\times 1000 $ Total charge on one small droplet is q and on the big drop is 1000q.

$ \Rightarrow \frac{V’}{V}=\frac{1000r}{R}=\frac{1000}{10}=100 $

$ \therefore V’=100V $



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