Question

A soap bubble is given a small negative charge. The radius of the soap bubble will

• A. decrease
• B. increases
• C. remains constant
• D. first increase then decrease

Answer 1

The correct option is B increases

The soap bubble is spherical in nature and the negative charges given to the soap bubble will get distributed uniformly.


Due to the presence of similar charges, repulsive forces will be developed which results in expansion of bubble.
Hence, the radius of the bubble will increase.

$\begin{array}{c}\text{Why this question ?}\\ \text{Tip: Soap solution acts as an electrolyte and}\\ \text{facilitates charge distribution in bubble.}\\ \text{Bottom line: Expansion of bubble will diminish the}\\ \text{repulsive forces by increasing distance among charges.}\end{array}$