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JEE Main 2022 (25 Jun, Shift 2) · Electric Potential & Equipotentials

Electric Potential & Equipotentials question from JEE Main 2022 (25 Jun, Shift 2)

Q70JEE Main 2022 · 25 JUN · SHIFT 2Easy

Electric Potential & Equipotentials

27 identical drops are charged at 22V each. They combine to form a bigger drop. The potential of the bigger drop will be _____________ V.

Numerical answer type. Work it out, then open the answer.

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Answer: 198

  1. Charge is conserved: Q=nqQ = nq; volume is conserved: 43πR3=n⋅43πr3⇒R=n1/3r\frac{4}{3}\pi R^3 = n\cdot\frac{4}{3}\pi r^3 \Rightarrow R = n^{1/3}r
  2. V′=kQR=knqn1/3r=n2/3VV' = \frac{kQ}{R} = \frac{knq}{n^{1/3}r} = n^{2/3}V
  3. V′=272/3×22=9×22=198 VV' = 27^{2/3}\times 22 = 9 \times 22 = 198\text{ V}
  4. So the answer is 198 V.
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