Surface tension of a soap bubble is 2.0×10−2 N m−1 . Work done to increase the radius of soap bubble from 3.5 cm to 7 cm will be : [Take π=227 ]

The work done to increase the radius of a soap bubble can be calculated using the formula for the work done on a bubble, which is:

W = 8πr₁r₂σ

where:

• W is the work done,
• r₁ and r₂ are the initial and final radii of the bubble,
• σ is the surface tension.

Given:

• σ = 2.0×10−2 N m−1,
• r₁ = 3.5 cm = 0.035 m (converted from cm to m),
• r₂ = 7 cm = 0.07 m (converted from cm to m),
• π = 22/7.

Substituting these values into the formula, we get:

W = 8 * (22/7) * 0.035 m * 0.07 m * 2.0×10−2 N m−1

Solving this, we get:

W = 0.024 Nm

So, the work done to increase the radius of the soap bubble from 3.5 cm to 7 cm is 0.024 Nm.