Question

Q.4 Find the surface tension in a soap bubble of 40 mm diameter when the inside

pressure is 2.5 N/m2 above atmospheric pressure.​

Answer 1

The surface tension on the bubble is σ  = 0.0125 N/m

Explanation:

We are given that:

• Diameter of soap bubble = 40 mm = 40 x 10^-3 m
• Inside pressure of the bubble = 2.5 N/m^2
• To Find: Surface tension = "σ" = ?

Solution:

The formula to find tension is given below;

Pressure = 8 x σ / d

2.5  = 8 x σ / 40 x 10^-3

σ  = 40 x 10^-3 x 2.5 / 8

σ  = 100 x 10^-3 / 8

σ  = 100 / 8000

σ  = 0.0125 N/m

Thus the surface tension on the bubble is σ  = 0.0125 N/m

Answer 2

Answer:

0.0817

0.0546

0.975

0.635