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MHT CET 2026 (14 May, Shift 1) · Force due to Surface Tension

Force due to Surface Tension question from MHT CET 2026 (14 May, Shift 1)

Q3MHT CET 2026 · 14 MAY · SHIFT 1Medium

Force due to Surface Tension

A drop of some liquid of volume 0.040.04 cm33 is placed on the surface of the glass plate. Then another glass plate is placed on it such that the liquid forms a thin layer of area 2020 cm22 between the surfaces. To separate the plates a force of 16×10516 \times 10^{5} dyne has to be applied normal to the surfaces. The surface tension of the liquid in dyne/cm is

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Answer: (c)

  1. Thickness of layer t=VA=0.0420=0.002 cmt = \frac{V}{A} = \frac{0.04}{20} = 0.002\text{ cm}.
  2. Force to separate plates: F=2ATt⇒T=Ft2AF = \dfrac{2AT}{t} \Rightarrow T = \dfrac{Ft}{2A}.
  3. T=16×105×0.0022×20=80 dyne/cmT = \dfrac{16\times10^5 \times 0.002}{2 \times 20} = 80\text{ dyne/cm}. So the answer is (c).
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