1000 small water drops each of capacitance c. join Together to form one large spherical drop. the capacitance of the bigger sphear is?

1 Answer
Mar 21, 2018

Volume of single big drop == Volume of 10001000 small drops

4/3 pi R^3=(4/3pi r^3)xx100043πR3=(43πr3)×1000
where RR is the radius of big drop and rr is the radius of small drop.
=>R=root (3)(1000r^3)R=31000r3
=>R=10rR=10r ........(1)

We know that electric potential on surface of sphere (drop) is

V_s=kq/rVs=kqr
where kk is Coulomb's Constant

Comparing with Q=CVQ=CV
we have

c=q/V_s=q/(kq/r)=r/kc=qVs=qkqr=rk ......(2)

Similarly Capacitance of big drop C_b=R/kCb=Rk ........(3)

From (2) and (3) we have

C_b/c=R/rCbc=Rr

Using (1) we get

C_b/c=(10r)/rCbc=10rr
=>C_b=10cCb=10c