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AP EAMCET · PHYSICS · Electrostatics

If 27 charged water droplets, each of radius \(10^{-3} \mathrm{~m}\) and charge \(10^{-12} \mathrm{C}\) coalesce to form a single big spherical drop, then the potential of the big drop is

  1. A 9 V
  2. B 27 V
  3. C 39 V
  4. D 81 V
Verified Solution

Answer & Solution

Correct Answer

(D) 81 V

Step-by-step Solution

Detailed explanation

\(R = n^{1/3} r = (27)^{1/3} \times 10^{-3} \mathrm{~m} = 3 \times 10^{-3} \mathrm{~m}\) \(Q = n q = 27 \times 10^{-12} \mathrm{~C}\) \(V = \frac{k Q}{R} = \frac{(9 \times 10^9 \mathrm{~N \cdot m^2 / C^2}) \times (27 \times 10^{-12} \mathrm{~C})}{3 \times 10^{-3} \mathrm{~m}}\)…