A U-shaped wire is dipped in a soap solution and removed. The thin soap film formed between the wire and the light slider supports a weight of $$1.5\times10^{-2}$$ N (which includes the small weight of the slider). The length of the slider is $$30$$ cm. The surface tension of the film is:
1. $$3.5\times10^{-2}$$ Nm-1
2. $$2.5\times10^{-2}$$ Nm-1
3. $$3.5\times10^{-3}$$ Nm-1
4. $$2.5\times10^{-3}$$ Nm-1

Subtopic:  Surface Tension |
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What is the pressure inside the drop of mercury of radius 3.00 mm at room temperature? The surface tension of mercury at that temperature () is 4.65 × 10–1 N m–1. The atmospheric pressure is 1.01 × 105 Pa.

Subtopic:  Surface Tension |
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What is the excess pressure inside a bubble of soap solution of radius $$5.00$$ mm?
(Given that the surface tension of soap solution at the temperature ($$20^{\circ}$$$$\text{C}$$) is $$2.5\times 10^{-2}$$ N/m)
1. $$10$$ Pa
2. $$20$$ Pa
3. $$1.06\times 10^{5}$$ Pa
4. $$15$$ Pa

Subtopic:  Surface Tension |
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Two narrow bores of diameters $$3.0$$ mm and $$6.0$$ mm are joined together to form a U-tube open at both ends. If the U-tube contains water, what is the difference in its levels in the two limbs of the tube? (The surface tension of water at the temperature of the experiment is $$7.3\times 10^{-2}$$ Nm–1. Take the angle of contact to be zero and the density of water to be $$1.0\times 10^{3}.$$ ($$g=9.8$$ ms–2)
1. $$4.95$$ mm
2. $$3.73$$ mm
3. $$8.91$$ mm
4. $$5.36$$ mm

Subtopic:  Surface Tension |
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