분야
pptxⅡ. Work 2(Unknown liquid)
Ⅲ. Work 3(Application)
At the constant radius, and for the curved surface, pressure differences can expressed by Laplace equation.
For Arbitary radius, pressure differences can expressed by the below equation.
Contact angle, θ
The contact angle θ is defined as the angle (measured in the liquid) that is formed at the junction of three phases
The Young’s equation shows the Equilibrium force balance in the three phases.
Behavior of Liquids in Capillary
This pressure difference due to the curved meniscus must be balanced by the hydrostatic pressure of the liquid column,
Experiment(Work 1)
Room temperature : 20ºC
Density of water : 1000kg / m3
Surface tension of water : 7.28X10-2N/m
Contact angle of water on the glass : 22.5º
Gravity : 9.81m/s2
R = r / cosΘ
For Comparison solution(Water)
Observation of a capillary phenomenon
Setting temperature : 20ºC in the room
Measurement of height of liquid in two capillary tubes
(Small tube and Large tube)
Calculation of the Surface tension(γ) of liquid
Assume that cosΘ ~ 0.9 (Contact angle : 22.5º ~ 30º)
Thus, γcosΘ value can give the information about Approximate value of Surface tension(γ)
γcosΘ value for the given liquids are computed
Assumption and Condition of experiment
Room temperature : 20ºC
Density of Glycerol : 1261kg/m3
Contact angle of Glycerol on the glass : 24.78º
Gravity : 9.81m/s2
Surface tention(γ) of each tubes
Surface tension of Glycerol is 63mN/m(Theoretical value)
Experimental error for small tube is noticeable!
For small tube, the Effect of gravity(g) makes error. Thus, large tube experiment is more correct.
Contact Angles for Liquid Drops at a Model Heterogeneous Surface Consisting of Alternating and Parallel Hydrophobic/Hydrophilic Strips
http://www.sciencetimes.co.kr/article.do?atidx=0000039632
http://blog.daum.net/whitebrow09/324
