MHT CET202019 Oct 2020Morning ShiftPhysicsMechanical Properties of FluidsActual
A water film is formed between the two straight parallel wires, each of length 10 cm , kept at a separation of 0 5 ~cm . Now, the separation between them is increased by 1 ~mm without breaking the water film. The work done for this is (surface tension of water =7 2 10⁻² Nm ⁻¹ )
Options
- A7 22 10⁻⁶ ~J
- B5 76 10⁻⁵ ~J
- C1 44 10⁻⁵ ~J
- D2 88 10⁻⁵ ~J
Correct answer
C. 1 44 10⁻⁵ ~J
Step-by-step solution
(A) Increase in the area of the film is A =10 ~cm 0.1 ~cm =1 ~cm ²=10⁻⁴ ~m ² Work done W=2 T . A array l =2 7.2 10⁻² 10⁻⁴ ~J =1.44 10⁻⁵ ~J array