Verified Solution • 2025–26 Session moderate

QJEEM13Phcb85: JEE Main 2013 Physics - Class 11 JEEM13Phcb85 Solution: Assume that a drop of liquid evaporates by decreases in its…

Assume that a drop of liquid evaporates by decreases in its surface energy, so that its temperature remains unchanged. What should be the minimum radius of the drop for this to be possible ? The surface tension is T, density of liquid is ρ and L is its latent heat of vaporization.

Multiple Choice Options

  • A ρL/T
  • B T/ρL
  • C T/ρL
  • D 2T/ρL

Step-by-Step Verified Solution

When radius is decrease by ΔR,
4πR2ΔRρL=4πT[R2−(R−ΔR)2]
⇒ρR2ΔRL=T[R2−R2+2RΔR−ΔR2]
⇒ρR2ΔRL=T2RΔR [ ΔR is very small ]
⇒R=2TρL

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