Class 12 NEET Physics Electrostatics Questions Part 1

Electric potential due to a charged sphere =

kQ

R

k=9×109N−m2∕C2
Q : charge on sphere
R : Radius of sphere
Let charge and radius of smaller drop is q and r respectively
For smaller drop, V=

kq

r

=220V
Let R be radius of bigger drop,
As volume remains the same
(

4

3

πr3)×27=

4

3

πR3
⇒R=3√27r=3r
Now, using charge conservation,
⇒Q=27q
Vbigdrop =

kQ

R

=

k(27q)

3r

=9(

kq

r

)
= 9 × 220 = 1980 V