A rectangular film of liquid is extended from ( 4 cm × 2 cm ) to ( 5 cm × 4 cm ) . If the work done is 3 ×…

A rectangular film of liquid is extended from (4 cm×2 cm) to (5 cm×4 cm). If the work done is 3×10-4 J, the value of the surface tension of the liquid is
  1. 0.250 N m-1
  2. 0.125 N m-1
  3. 0.2 N m-1
  4. 8.0 N m-1

Solution

W=2Af-AiT

⇒T=WAf-Ai×2

=3×10-4 J25×4×10-4-4×2×10-4

=0.125 N m-1

Asked in: MHT CET Full Test 13

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