Question

A wire frame 5 cm in length forms a liquid film.
Calculate the surface tension of the liquid if the
net force lifting the frame is 7.5 x 10-2 N.​

Answer 1

Given:

• Net force = 7.5 × 10^(-2) N.
• Length = 5 cm

To find:

• Surface tension of the liquid ?

Calculation:

Surface tension on the surface of any liquid is defined as the force per unit length. Otherwise it can also be defined as the surface energy per unit surface area.

• Let surface tension be T :

$T = \dfrac{force}{length}$

$\implies T = \dfrac{7.5 \times {10}^{ - 2} }{( \dfrac{5}{100}) }$

$\implies T = \dfrac{7.5 \times {10}^{ - 2} }{0.05}$

$\implies T = \dfrac{7.5 \times {10}^{ - 2} }{5 \times {10}^{ - 2} }$

$\implies T = \dfrac{7.5 }{5 }$

$\implies T = 1.5 \: N/m$

So, surface tension of liquid is 1.5 N/m.