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MHT CET 2025 (25 Apr, Shift 2) · Electric Potential & Equipotentials

Electric Potential & Equipotentials question from MHT CET 2025 (25 Apr, Shift 2)

Q29MHT CET 2025 · 25 APR · SHIFT 2Easy

Electric Potential & Equipotentials

Assuming the drops to be spherical, 27 identical drops of mercury are charged simultaneously to the same potential of 20 volt. If all the charged drops are made to combine to form one big drop, then potential of big drop will be

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Answer: (b)

Charge is conserved: $Q = nq$ ; volume is conserved: $\frac{4}{3}\pi R^3 = n\cdot\frac{4}{3}\pi r^3 \Rightarrow R = n^{1/3}r$
$V' = \frac{kQ}{R} = \frac{knq}{n^{1/3}r} = n^{2/3}V$
$V' = 27^{2/3}\times 20 = 9 \times 20 = 180\text{ V}$
So the answer is (b) 180 V.

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