You visited us 1 times! Enjoying our articles? Unlock Full Access!

Byju's Answer

Standard VIII

Chemistry

Surface Tension

A soap bubble...

Question

A soap bubble of radius ' $r$ ' is formed in air. The excess pressure inside the bubble is:

\frac{4 T}{r}

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

\frac{2 T}{r}

No worries! We‘ve got your back. Try BYJU‘S free classes today!

P_{o} + \frac{2 T}{r}

No worries! We‘ve got your back. Try BYJU‘S free classes today!

P_{o} - \frac{4 T}{r}

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is A $\frac{4 T}{r}$
When the air bubble is present in air, there are two surfaces-first, the air to water bubble surface where the pressure increases, and second, the water to air surface inside the bubble where the pressure again increases.
Hence the excess pressure inside the bubble is the increases in pressure across two surfaces= $2 \times \frac{2 T}{r}$
$= \frac{4 T}{r}$

Suggest Corrections

Similar questions

Q. If the excess pressure inside a soap bubble of radius

r_{1}

in air is equal to the excess pressure inside air bubble of radius

r_{2}

inside the soap solution, then

r_{1} : r_{2}

Q. The excess pressure across a soap bubble of radius

r

p = \frac{4 σ}{r},

where

σ

is the surface tension of soap solution. What is the excess pressure across an air bubble of the same radius

r

formed inside a container of soap solution?

A bubble having surface tension T and radius R is formed on a ring of radius b (b << R). Air is blown inside the tube with velocity v as shown. The air molecules collide perpendicularly with the wall of the bubble and stops. Calculate the radius at which the bubble separates from the ring.

Q. Two soap bubbles of the same radius

r

coalesce isothermally to form a bigger bubble of radius

R

. If the atmospheric pressure is

P_{o}

, find the surface tension of the soap solution.

Q. Match List -I with List-II

List-I	List-II
a) Radius of the common surface when two soap bubbles of radii $R_{1} a n d R_{2}$ coalesce.	e) $(R_{1}^{3} + R_{2}^{3})^{1 / 3}$
b) Radius of the large drop when two liquid drops of radii $R_{1} a n d R_{2}$ combine at constant temperature.	f) $\frac{R_{1} R_{2}}{R_{2} - R_{1}}$
c) Excess of pressure inside air bubble.	g) $\frac{2 T}{r}$
d) Excess of pressure in the air bubble in water.	h) $\frac{4 T}{r}$

The correct match is:

Join BYJU'S Learning Program

A soap bubble of radius 'r' is formed in air. The excess pressure inside the bubble is:

A soap bubble of radius ' $r$ ' is formed in air. The excess pressure inside the bubble is: