Solution
Related Formula
V = (kq)/(r) Volume Conservation: N · ((4)/(3)π r³) = (4)/(3)π R³Core Logic
From volume conservation of 3 coalescing droplets:
3 ((4)/(3)π r³) = (4)/(3)π R³ R = 31/3rTotal charge on resultant bigger bubble Q = 3q.
Calculating initial potential Vᵢ and final potential Vf:
Vᵢ = (kq)/(r) Vf = (k(3q))/(R) = 3kq31/3r = 32/3 (kq)/(r)Ratio of initial to final potential:
(Vᵢ)/(Vf) = 132/3 = 1 : 32/3Step 1: Final Conclusion
The ratio of potentials is 1 : 32/3.
Pattern Recognition
Coalescing droplets rule: For N identical drops, R = N1/3r and Q = Nq. Potential ratio Vᵢ / Vf = 1 / N2/3. For N=3, ratio is 1 / 32/3.
Chapter Mix
Class 12 Physics: Electrostatic Potential and Capacitance