Question

Area of liquid film is 6×10cm2 and surface tension is t20 dyne /cm what is work done to change are up to 12 × 10

Answer 1

Initial Area = 6 × 10 cm²

Final Area = 12 × 10 cm²

Surface Tension (T or S) = 20 dyne/cm.

Now, Using the Formula,

Work done = Change in area × Surface Tension

∴ Work done = (120 - 60) × 20

∴ Work done = 60 × 20

⇒ Work done = 1200 erg.

Since, the film is considered as double layered, therefore, Total work done = 2 × 1200 erg.  

= 2400 erg.

Hope it helps .

Answer 2

Initial Area = 6 × 10 cm²

Final Area = 12 × 10 cm²

Surface Tension (T or S) = 20 dyne/cm.


Now, Using the Formula,

Work done = Change in area × Surface Tension

∴ Work done = (120 - 60) × 20

∴ Work done = 60 × 20

⇒ Work done = 1200 erg.


Since, the film is considered as double layered, therefore, Total work done = 2 × 1200 erg.  

= 2400 erg.