AP EAPCET 08-Jul-2022 Shift 1 Paper

For evaporation water pressure (excess pressure due to surface tension) is greater than vapor pressure.
⇒ Excess pressure in drop ≥ vapor pressure
⇒

2T

R

≥p
where, T= surface tension
p= vapor pressure
R= Radius of drop
⇒R=

2T

p

Here, surface tension, T=8×10−2N∕m
vapor pressure, p=25×103‌Pa
Hence, radius of drop R=

2×8×10−2

25×103

⇒R=

16

25

×10−4m
⇒R=64×10−6m=64µm