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The work done in increasing the size of a soap film from 10 cm × 6 cm to 10 cm × 11 cm is 3 × 10 - 1 J . The surface tension of the film is

Options

  1. A1.5 × 10 − 2 N m - 1
  2. B3.0 × 10 − 2 N m - 1
  3. C6.0 × 10 − 2 N m - 1
  4. D11.0 × 10 − 2 N m - 1

Correct answer

B. 3.0 × 10 − 2 N m - 1

Step-by-step solution

W = T × Δ A ∴ T = W Δ A T = 3 × 10 − 4 2 × ( 110 − 60 ) × 10 − 4 (Soap film has two surfaces) = 3 × 10 − 2 N m - 1

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