A rectangular film of liquid is extended from (4cm×2cm) to (5cm×4cm). If the work done is 3\times 10^{-4}J, the value of the surface tension of the liquid is

Initial area of the film Ai=4×2=8 cm2=8×10−4 m2Final area of the film Af=5×4=20 cm2=20×10−4 m2Thus change in area ΔA=(20−8)×10−4=12×10−4 m2Work done W=3×10−4 JUsing for soap films W=S(2ΔA) where S is the surface tension∴ 3×10−4=S×2×12×10−4 ⟹S=0.125 Nm−1

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A rectangular film of liquid is extended from (4cm 2cm) to (5c

Question

A rectangular film of liquid is extended from $(4 c m \times 2 c m)$ to $(5 c m \times 4 c m)$ . If the work done is 3\times 10^{-4}J$$, the value of the surface tension of the liquid is

8.0 N m^{- 1}

0.250 N m^{- 1}

0.125 N m^{- 1}

0.2 N m^{- 1}

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A rectangular film of liquid is extended from

(4 c m \times 2 c m)

(5 c m \times 4 c m)

. If the work done is 3\times 10^{-4}J$$, the value of the surface tension of the liquid is

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Text solutionVerified

Initial area of the film

A_{i} = 4 \times 2 = 8

c m^{2} = 8 \times 1 0^{- 4}

m^{2}

Final area of the film

A_{f} = 5 \times 4 = 20

c m^{2} = 20 \times 1 0^{- 4}

m^{2}

Thus change in area

Δ A = (20 - 8) \times 1 0^{- 4} = 12 \times 1 0^{- 4}

m^{2}

Work done

W = 3 \times 1 0^{- 4}

Using for soap films

W = S (2Δ A)

where

S

is the surface tension

∴

3 \times 1 0^{- 4} = S \times 2 \times 12 \times 1 0^{- 4}

⟹ S = 0.125

N m^{- 1}

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Question Text	A rectangular film of liquid is extended from $(4 c m \times 2 c m)$ to $(5 c m \times 4 c m)$ . If the work done is 3\times 10^{-4}J$$, the value of the surface tension of the liquid is
Answer Type	Text solution:1
Upvotes	150

A rectangular film of liquid is extended from (4cm×2cm) to (5cm×4cm). If the work done is 3\times 10^{-4}J$$, the value of the surface tension of the liquid is

Text solutionVerified

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A rectangular film of liquid is extended from $(4 c m \times 2 c m)$ to $(5 c m \times 4 c m)$ . If the work done is 3\times 10^{-4}J$$, the value of the surface tension of the liquid is