Start free

Physics · Electrostatics

JEE Main 2026 — 22 January, Evening Shift — Question 30

Three small identical bubbles of water having same charge on each coalesce to form a bigger bubble. Then the ratio of the potentials on one initial bubble and that on the resultant bigger bubble is :

  1. Option A:

    1:31/31: 3^{1 / 3}

  2. Option B:

    1:22/31: 2^{2 / 3}

  3. Option C:

    32/3:13^{2 / 3}: 1

  4. Option D:

    1:32/31: 3^{2 / 3}

    Correct

Answer: D

Step-by-step solution

Using volume conservation

3(43πr3)=(43πR3)R=31/3r\begin{aligned} & 3\left(\frac{4}{3} \pi r^{3}\right)=\left(\frac{4}{3} \pi R^{3}\right) & R=3^{1 / 3} r \end{aligned} ViVf=kqrk3qR=R3r=31/3r3r=132/3\frac{V_{i}}{V_{f}}=\frac{\frac{k q}{r}}{\frac{k 3 q}{R}}=\frac{R}{3 r}=\frac{3^{1 / 3} r}{3 r}=\frac{1}{3^{2 / 3}}

Answer key and solution verified before publishing.

Practise Electrostatics

Start with this question, then two more from the same chapter — with a tutor that explains every step. Free.

Solve a similar one free
Exam
JEE Main 2026
Paper
22 January, Evening Shift
Subject
Physics
Chapter
Electrostatics
Topic
Properties of Conductors and Redistribution of Charge