A liquid drop evaporates only by decrease of its surface energy, so its temperature remains constant. If surface tension is T, density is ρ and latent heat of vaporization is L, find the minimum possible drop radius.
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Question

A liquid drop evaporates only by decrease of its surface energy, so its temperature remains constant. If surface tension is T, density is ρ and latent heat of vaporization is L, find the minimum possible drop radius.

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G1 Physics · Accepted Answer

Step 1: Use surface-energy/pressure relations: ΔP = 2T/R for a liquid drop or 4T/R for a soap bubble, capillary rise h = 2T cosθ/(ρgr), and surface energy = TΔA. Step 2: Apply force or energy balance to the stated radii and surface areas. Applying these relations to the given data gives D: 2T/(ρₗ). Final answer: D.