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 $
