NEET2021PhysicsElectrostaticsActual
Twenty seven drops of same size are charged at 220   V each. They combine to form a bigger drop. Calculate the potential of the bigger drop.
Options
- A660   V
- B1320   V
- C1980   V
- D1520   V
Correct answer
C. 1980   V
Step-by-step solution
The radius of the bigger drop will be 4 3 π R 3 = 27 × 4 3 π r 3 ⇒ R = 3 r , the potential of the small drop, V = K q r . The potential of the big drop Q = n q ,   V ' = K Q R ⇒ V ' = K n q R As we know, V '   = n 2 / 3 V = ( 27 ) 2 / 3 × 220 = 1980   V