What is the potential energy of the soap film formed on a frame of area 4 × 10-3 m2 ? If the area of the film is reduced by half, the change in its potential energy will be (Surface tension of the soap solution is 10-3 N / m )

Question

What is the potential energy of the soap film formed on a frame of area 4 × 10-3 m2 ? If the area of the film is reduced by half, the change in its potential energy will be (Surface tension of the soap solution is 10-3 N / m ) (A) 32 × 10-5 J, 16 × 10-5 J (B) 16 × 10-5 J, 8 × 10-5 J (C) 48 × 10-5 J, 12 × 10-5 J (D) 36 × 10-5 J ,2 × 10-5 J

Tardigrade Admin · Accepted Answer

Potential energy of the film =2 T A =2 × 40 × 10-3 × 4 × 10-3 =32 × 10-5 J Change in potential energy =2 T Δ A =2 × 40 × 10-3[4 × 10-3-2 × 10-3] =16 × 10-5 J

Q. What is the potential energy of the soap film formed on a frame of area $4 \times 1 0^{- 3} m^{2}$ ? If the area of the film is reduced by half, the change in its potential energy will be (Surface tension of the soap solution is $1 0^{- 3} N / m$ )

$32 \times 1 0^{- 5} J, 16 \times 1 0^{- 5} J$

$16 \times 1 0^{- 5} J, 8 \times 1 0^{- 5} J$

$48 \times 1 0^{- 5} J, 12 \times 1 0^{- 5} J$

$36 \times 1 0^{- 5} J, 2 \times 1 0^{- 5} J$

Potential energy of the film
$= 2 T A$
$= 2 \times 40 \times 1 0^{- 3} \times 4 \times 1 0^{- 3}$
$= 32 \times 1 0^{- 5} J$
Change in potential energy
$= 2 T Δ A$
$= 2 \times 40 \times 1 0^{- 3} [4 \times 1 0^{- 3} - 2 \times 1 0^{- 3}]$
$= 16 \times 1 0^{- 5} J$

Q. What is the potential energy of the soap film formed on a frame of area 4×10−3m2 ? If the area of the film is reduced by half, the change in its potential energy will be (Surface tension of the soap solution is 10−3N/m )

32×10−5J,16×10−5J

16×10−5J,8×10−5J

48×10−5J,12×10−5J

36×10−5J,2×10−5J