If work W is done in blowing a bubble of radius R from a soap solution, then the work done in blowing a bubble of radius 2R from the same solution is
Correct Answer :
4W
Solution :
The correct option is 4W.
Step-by-step Explanation:
When a soap bubble is blown in air, it has two free surfaces (an inner surface and an outer surface) in contact with the air.
The work done in blowing a soap bubble of radius is equal to the increase in its surface energy.
The formula for the work done in blowing a soap bubble of radius with surface tension is given by:
where is the surface area of a sphere of radius , which is .
Substituting the area into the equation:
From this expression, we can see that since the surface tension of the same soap solution remains constant, the work done is directly proportional to the square of the radius of the bubble:
Let be the work done for a bubble of radius .
Let be the work done for blowing a bubble of radius .
Taking the ratio of the work done in both cases:
Substituting the given values:
Therefore, the work done in blowing a bubble of radius 2R from the same solution is 4W.
Access expert-curated educational resources and study materials—completely free.
Create, conduct, and manage professional online assessments with Crey. Perfect for teachers and institutes.
Copyright © 2026 Crey. All Rights Reserved.