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
\(\frac{\Delta T}{T} \times100 = \frac{\Delta D}{D} \times100 + \frac{\Delta h}{h} \times100\)
\(= \frac{0.01}{1.25} \times100 + \frac{0.01}{1.45} \times100\)
\(= \frac{100}{125} + \frac{100}{145}\)
\(= 0.8 + 0.689\)
\(= 1.489\) \(\simeq 1.5 \%\)
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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.