Question

Radius of a soap bubble is increased from R to 2R work done in this process in terms of surface tension is

• A. $24 \pi R ^ { 2 } S$
• B. $48 \pi R ^ { 2 } S$
• C. $12 \pi R ^ { 2 } S$
• D. $36 \pi R ^ { 2 } S$

Answer 1

Answer: (A)

$24 \pi R ^ { 2 } S$

Answer 2

$W = 8 \pi T \left( R _ { 2 } ^ { 2 } - R _ { 1 } ^ { 2 } \right)$ $= 8 \pi S \left[ ( 2 R ) ^ { 2 } - ( R ) ^ { 2 } \right]$ $= 24 \pi R ^ { 2 } S$