Question

Sixty four conducting drops each of radius 0.02 m and each carrying a charge of 5 µC are combined to form a bigger drop. The ratio of surface density of bigger drop to the smaller drop will be : 

(A) 1 : 4 

(B) 4 : 1 

(C) 1 : 8 

(D) 8 : 1

Answer 1

Correct option is (B) 4 : 1

Let R = radius of combined drop 

r = radius of smaller drop 

Volume will remain same

q : charge of smaller drop 

Q : Charge of combined drop