Liquid surface tension coefficient measuring device

Abstract

The invention discloses a liquid surface tension coefficient measuring device. A force sensor is arranged on a support frame; the support frame is fixedly arranged on a base; a culture dish for containing liquid to be tested is arranged right under a hanging ring; an opening formed in the bottom of a sleeve is connected with one end of a hose; the other end of the hose is provided with two branchpipes; a one-way valve is connected onto one branch pipe; a flow limiting valve is connected onto the other branch pipe; liquid is contained in a liquid tank; a compression block is glidingly matchedwith the upper part of the liquid tank; a thin sheet suspends on the surface of the liquid to be tested in the culture disk; the diameter of the thin sheet is smaller than the inner diameter of the hanging ring. A liquid membrane is lifted by the hanging ring in a hydraulic mode; the liquid membrane generates slow and uniform changes; the vibration is small, so that the measurement precision is ensured. By the scheme, the suspended thin sheet is additionally added in the liquid to be tested; the waist collection degree during the liquid membrane pulling can be effectively reduced by the thin sheet, so that when the inner diameter*2 of the hanging ring is used as the boundary length 1, the errors are small.

Description

technical field [0001] The invention belongs to the field of physics teaching experiments, and in particular relates to a measuring device for the coefficient of surface tension of a liquid. Background technique [0002] The experiment of measuring the surface tension of a liquid by the pull-off method is a classic experimental project in the "General University Physics Experiment". The measurement system used in this experiment is very conventional and mature. It is used to measure the surface tension coefficient of a liquid, and a force-sensitive sensor is used as a force sensor to measure force Variety. In the experimental measurement system, the force-sensitive sensor is fixed, and the lifting ring is suspended on the force-sensitive sensor. The rising liquid level contacts the lifting ring, and the ring-shaped liquid film is pulled up on the lifting ring. As the liquid level gradually drops, the force on the force sensor changes accordingly. The force change on the fo...

AI Technical Summary

Problems solved by technology

Due to the rapid change of the tension before and after the liquid film breaks, it is not easy to observe the change of the tension before and after the break through the real-time display digital display

Moreover, in experimental teaching, students tend to use the difference between the maximum value of force and the stable value of force after fracture as the measurement value of surface tension, which will also lead to inaccurate measurement

[0006] 3. The existing measurement system has no heating and temperature control devices, and cannot carry out variable temperature experiments, and temperature is an influencing factor of the surface tension of liquids, so it is impossible to further study the specific influence of temperature on the surface tension of liquids, thus limiting the in-depth academic research carry out

It should be noted that, for a liquid film with no obvious waist (such as water with poor surface activity), the pulled-up liquid film is in the shape of a cylinder, and when π*(D1+D2) is used as the length of the dividing line l, α The calculation error is less; for the liquid film with obvious waist (such as the water and detergent mixture with strong surface activity), the waist refers to that the two ends of the liquid film are large and the middle is small, and π*(D1+ D2) As the length l of the dividing line, it will lead to a large calculation error of α

Images