Question

Under is thermal condition two soap bubbles of radii a and b coalesce to forma single bubble of radius c. If the external pressure is p₀ show that surface tension, 

Answer 1

As excess pressure for a soap bubble is(4T/r) and external pressure p₀ ,

Now as mass is conserved,

As temp. is constant, i.e., T_a = T_b = T_c ,so the above expression reduces to

p_a V_a + p_b V_b = p_c V_c

Which in the light of Eqn. (1) and (2) becomes