$64$ identical drops each charged upto potential of $10\,mV$ are combined to form a bigger dorp. The potential of the bigger drop will be $..........\,mV$
JEE MAIN 2023, Medium
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Let $q =$ charge on each drop
$V =\frac{ Kq }{ r } \text {-.- (1) }$
Now for combination of 64 drop
$64 \times \frac{4}{3} \pi r^3=\frac{4}{3} \pi R^3$
$R=4 r$
And $Q =64 q$
Potential of bigger drop
$=\frac{ KQ }{ R }=\frac{ K 64 q }{4 r }=16 \frac{ Kq }{ r }$
$=16 \times 10\,mV =160\,mV$
Correct answer is $160 .$
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