The following observations were taken for determining surface tension T of water by capillary method: diameter of capillary, \(D = 1.25 \times 10^{-2} \, m\)rise of water, \(h = 1.45 \times 10^{-2} m\). Using \(g = 9.80 \, m/s^2\) and the simplified relation \(T = \frac{rhg}{2} \times 10^3 \, N/m\) , the possible error in surface tension is closest to:
- $0.15\%$
- $1.5\%$
- $2.4\%$
- $10\%$
The Correct Option is B
Solution and Explanation
\(\frac{\Delta T}{T} \times100 = \frac{\Delta D}{D} \times100 + \frac{\Delta h}{h} \times100\)
\(= \frac{0.01}{1.25} \times100 + \frac{0.01}{1.45} \times100\)
\(= \frac{100}{125} + \frac{100}{145}\)
\(= 0.8 + 0.689\)
\(= 1.489\) \(\simeq 1.5 \%\)
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
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
A bead of mass \( m \) slides without friction on the wall of a vertical circular hoop of radius \( R \) as shown in figure. The bead moves under the combined action of gravity and a massless spring \( k \) attached to the bottom of the hoop. The equilibrium length of the spring is \( R \). If the bead is released from the top of the hoop with (negligible) zero initial speed, the velocity of the bead, when the length of spring becomes \( R \), would be (spring constant is \( k \), \( g \) is acceleration due to gravity):
- JEE Main - 2025
- Fluid Mechanics
- Let \( f: \mathbb{R} \to \mathbb{R} \) be a function defined by \( f(x) = \left( 2 + 3a \right)x^2 + \left( \frac{a+2}{a-1} \right)x + b, a \neq 1 \). If \[ f(x + y) = f(x) + f(y) + 1 - \frac{2}{7}xy, \] then the value of \( 28 \sum_{i=1}^5 f(i) \) is:
- JEE Main - 2025
- Functions
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.