Question

the surface tension of soap solution is 25×10^-3 NM^-1. the excess pressure inside a soap bubble of diameter 1 cm is ​

Answer 1

The excess pressure is calculated as ΔP=  

r

4T

​  

 

ΔP=  

0.5×10  

−2

 

4×25×10  

−3

 

​  

=20N/m  

2

 

1Pa=1N/m  

2

 

⇒ΔP=20Pa

Option C is correct.