27 similar drops of mercury are maintained at 10 V each. All these spherical drops combine into a single big drop. The potential energy of the bigger drop is ____ times that of a smaller drop.
Answer: 243
Solution
Mercury is incompressible, so gives , while the charges add to . The potential of the large drop is
The electrostatic energy of a charged conducting drop is , so
The energy of the big drop is times that of a small drop.
The electrostatic energy of a charged conducting drop is , so
The energy of the big drop is times that of a small drop.
JEE Main · 2021 · 26 Feb 2021 · Shift 2 · Integer answer