Two soap bubbles coalesce to form a single bubble. If $V$ is the subsequent change in volume of contained air and $S$ the change in total surface area, $T$ is the surface tension and $P$ atmospheric pressure, which of the following relation is correct ?
- 4PV + 3ST = 0
- 3PV + 4ST = 0
- 2PV + 3ST = 0
- 3PV + 2ST = 0
The Correct Option is B
Solution and Explanation
$\left( P +\frac{4 T }{ r _{1}}\right) \frac{4}{3} \pi r _{1}^{3}+\left( P +\frac{4 T }{ r _{2}}\right) \frac{4}{3} \pi r _{2}^{3}$
$=\left( P +\frac{4 T }{ r }\right) \frac{4}{3} \pi r ^{3}$
$PV +\frac{4 T }{3}\left(4 \pi r _{1}^{2}+4 \pi r _{2}^{2}-4 \pi r ^{2}\right)$
$3 pv +4 TS$
Top Questions on Surface Tension
- A capillary tube of radius 0.1 mm is partly dipped in water (surface tension 70 dyn/cm and glass water contact angle $ \approx 0^\circ $) with $ 30^\circ $ inclined with vertical. The length of water risen in the capillary is ____ cm. (Take $ g = 9.8 $ m/s$^2 $)
- JEE Main - 2025
- Physics
- Surface Tension
Consider a water tank shown in the figure. It has one wall at \(x = L\) and can be taken to be very wide in the z direction. When filled with a liquid of surface tension \(S\) and density \( \rho \), the liquid surface makes angle \( \theta_0 \) (\( \theta_0 < < 1 \)) with the x-axis at \(x = L\). If \(y(x)\) is the height of the surface then the equation for \(y(x)\) is: (take \(g\) as the acceleration due to gravity)
- NEET (UG) - 2025
- Physics
- Surface Tension
- A spherical air bubble is formed inside a liquid (like water). The radius of the bubble is 0.5 mm, and the surface tension of the liquid is 0.072 N/m. What is the pressure inside the bubble relative to the outside pressure?
- MHT CET - 2025
- Physics
- Surface Tension
- A balloon is made of a material of surface tension S and has a small outlet. It is filled with air of density \( \rho \). Initially the balloon is a sphere of radius R. When the gas is allowed to flow out slowly at a constant rate, its radius shrinks as \( r(t) \). Assume that the pressure inside the balloon is \( P(r) \) and is more than the outside pressure (\( P_0 \)) by an amount proportional to the surface tension and inversely proportional to the radius. The balloon bursts when its radius reaches \( r_0 \). Then the speed of gas coming out of the balloon at \( r = R \) is :
- NEET (UG) - 2025
- Physics
- Surface Tension
- When the angle of contact between a solid and a liquid is \( 90^\circ \), then
- UPCATET - 2025
- Physics
- Surface Tension
Questions Asked in JEE Main exam
The motion of an airplane is represented by the velocity-time graph as shown below. The distance covered by the airplane in the first 30.5 seconds is km.
- JEE Main - 2025
- Kinematics
The least acidic compound, among the following is
- JEE Main - 2025
- Organic Chemistry
Choose the correct set of reagents for the following conversion:
- JEE Main - 2025
- Organic Chemistry
- JEE Main - 2025
- Organic Chemistry
- In a group of 3 girls and 4 boys, there are two boys \( B_1 \) and \( B_2 \). The number of ways in which these girls and boys can stand in a queue such that all the girls stand together, all the boys stand together, but \( B_1 \) and \( B_2 \) are not adjacent to each other, is:
- JEE Main - 2025
- Permutations
Concepts Used:
Surface Tension
The amount of energy required to increase the liquid's surface area by one unit area is known as surface tension. In other words, it is a property of the liquid surface to resist force.
Surface tension is defined as,
The ratio of the surface force F to the length L along which the force acts.
Mathematically, the surface tension formula can be expressed as follows:
T=F/L
Where,
- F is the force per unit length
- L is the length in which force act
- T is the surface tension of the liquid
Read More: Detergents and Surface Tension
Factors affecting surface tension:
- Impurities: The surface tension decreases with the addition of impurities.
- Surfactants: Adding surfactants in liquids lowers the tension of water making it interrupt aside or get susceptible.
- Temperature: The surface tension of a liquid reduces as the temperature rises.
The Unit of Surface Tension:
The SI unit of Surface Tension is Newton per Meter or N/m.