JEE Main 2024 Physics question
A soap bubble is blown to a diameter of 7 cm. 36960 erg of work is done in blowing it further. If surface tension of soap solution is 40 dyne/cm then the new radius is cm. Take
Answer: 7
Solution
W = 8πT(r₂² − r₁²): 36960 = 8 × (22/7) × 40 × (r₂² − 12.25) ⇒ r₂² = 49.