Search results
Results from the WOW.Com Content Network
The drop falls when the weight (mg) is equal to the circumference (2πr) multiplied by the surface tension (σ). The surface tension can be calculated provided the radius of the tube (r) and mass of the fluid droplet (m) are known. Alternatively, since the surface tension is proportional to the weight of the drop, the fluid of interest may be ...
Surface tension is an important factor in the phenomenon of capillarity. Surface tension has the dimension of force per unit length, or of energy per unit area. [3] The two are equivalent, but when referring to energy per unit of area, it is common to use the term surface energy, which is a more general term in the sense that it applies also to ...
The limit of this formula, as α goes to 90°, gives the maximum weight of a pendant drop for a liquid with a given surface tension, . m g = π d γ {\displaystyle \,mg=\pi d\gamma } This relationship is the basis of a convenient method of measuring surface tension, commonly used in the petroleum industry.
A device used for such measurements is called a “spinning drop tensiometer”. The spinning drop method is usually preferred for the accurate measurements of surface tensions below 10 −2 mN/m. It refers to either using the fluids with low interfacial tension or working at very high angular velocities.
Force per unit oriented surface area Pa L −1 M T −2: order 2 tensor Surface tension: γ: Energy change per unit change in surface area N/m or J/m 2: M T −2: Thermal conductance κ (or) λ: Measure for the ease with which an object conducts heat W/K L 2 M T −3 Θ −1: extensive Thermal conductivity: λ: Measure for the ease with which a ...
The surface energy is measured in units of joules per square meter, which is equivalent in the case of liquids to surface tension, measured in newtons per meter.The overall surface tension/energy of a liquid can be acquired through various methods using a tensiometer or using the pendant drop method and maximum bubble pressure method.
Advancing and receding contact angles can be measured directly from the same measurement if drops are moved linearly on a surface. For example, a drop of liquid will adopt a given contact angle when static, but when the surface is tilted the drop will initially deform so that the contact area between the drop and surface remains constant.
The Wilhelmy plate tensiometer requires a plate to make contact with the liquid surface. It is widely considered the simplest and most accurate method for surface tension measurement. Due to a large wetted length of the platinum plate, the surface tension reading is typically very stable compared to alternative methods.