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

Question

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 (A) 0.250 N m- 1 (B) 0.125 N m- 1 (C) 0.2 N m- 1 (D) 8.0 N m- 1

Tardigrade Admin · Accepted Answer

W=2(Af - Ai)T ⇒ T=(W/(Af - Ai) × 2) =(3 × 10- 4 J/2 [5 × 4 × 10- 4 - 4 × 2 × 10- 4]) =0.125 N m- 1

Q. 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 $3 \times 1 0^{- 4} J$ , the value of the surface tension of the liquid is

$0.250 N m^{- 1}$

$0.125 N m^{- 1}$

$0.2 N m^{- 1}$

$8.0 N m^{- 1}$

$W = 2 (A_{f} - A_{i}) T$
$\Rightarrow T = \frac{W}{( A _{f} - A _{i} ) \times 2}$
$= \frac{3 \times 1 0 ^{- 4} J}{2 [ 5 \times 4 \times 1 0 ^{- 4} - 4 \times 2 \times 1 0 ^{- 4} ]}$
$= 0.125 N m^{- 1}$

Q. A rectangular film of liquid is extended from (4cm×2cm) to (5cm×4cm) . If the work done is 3×10−4J , the value of the surface tension of the liquid is

0.250Nm−1

0.125Nm−1

0.2Nm−1

8.0Nm−1