A teaching demonstration tool for liquid surface tension

Abstract

This utility model discloses a teaching demonstration tool for liquid surface tension, comprising: a liquid container with an internal chamber for holding liquid, the liquid container being made of a liquid-repellent material; at least one rectangular opening is formed on the side wall of the liquid container, the long side of the rectangular opening extending through the side wall along the vertical direction of the liquid container, and the width W of the rectangular opening satisfying: W≤2σH / (ρgH) 2 -2σ), where σ is the surface tension coefficient of the liquid in the liquid container, ρ is the density of the liquid in the liquid container, g is the gravitational coefficient, and H is the preset maximum demonstration height value, where H represents the height at which the liquid in the liquid container is above the bottom of the rectangular opening and remains inside the liquid container without flowing out of the rectangular opening. This utility model provides a liquid surface tension teaching demonstration tool that can be used to conduct heuristic and exploratory scientific experiments, effectively stimulating students' desire for knowledge and achieving the effect of learning through play.

Description

Technical Field

[0001] This utility model relates to the field of teaching aids technology, specifically to a teaching demonstration tool for liquid surface tension. Background Technology

[0002] Liquid surface tension is an important topic in physics and popular science education. The theoretical explanations are not only obscure and difficult to understand, but also contradict conventional knowledge and are hard to believe. However, existing experimental demonstration methods are limited and require teachers to make their own tools, making demonstrations difficult and compromising on success rates.

[0003] For example, the article [Xu Hui, Zhou Yuanhong, Several Demonstration Experiments Related to Surface Tension [J], Physics Bulletin, 2020, 49(S02):91-9295] summarizes some teaching demonstration methods for liquid surface tension, mainly involving teaching tools such as soap film, soapy water, suspended matter, and glass tubes. However, in actual teaching, there are problems such as the cumbersome process of preparing soapy water and making soap film, and the inability to guarantee the success rate; the need to observe suspended matter from above, resulting in poor demonstration effects; and the high risk factor and inability to reuse glass tubes.

[0004] Therefore, it is necessary to design a teaching demonstration tool that is simple in structure, easy to operate, has a high success rate, excellent demonstration effect, and can be reused for the important physics teaching content of liquid surface tension, so as to better carry out experimental teaching and popular science teaching related to the physics theory of "liquid surface tension".

[0005] In view of the above, this utility model is hereby proposed. Utility Model Content

[0006] To solve the above-mentioned technical problems, this utility model proposes a teaching demonstration tool for liquid surface tension, specifically adopting the following technical solution:

[0007] A demonstration tool for teaching liquid surface tension includes:

[0008] A liquid container having an internal chamber for holding liquid, the liquid container being made of a liquid-repellent material;

[0009] At least one rectangular opening is formed on the side wall of the liquid container, the longer side of the rectangular opening extending through the side wall along the vertical direction of the liquid container, and the width W of the rectangular opening satisfies: W≤2σH / (ρgH) 2 -2σ), where σ is the surface tension coefficient of the liquid in the liquid container, ρ is the density of the liquid in the liquid container, g is the gravity coefficient, H is the preset maximum demonstration height value, and H represents the height at which the liquid is above the bottom of the rectangular opening in the liquid container and remains inside the liquid container without flowing out of the rectangular opening.

[0010] As an optional embodiment of this utility model, a rectangular opening is formed on the side wall of the liquid container, and the maximum demonstration height value H is less than or equal to the length of the long side of the rectangular opening.

[0011] As an optional embodiment of this utility model, multiple rectangular openings are formed on the side wall of the liquid container, and the length of the long side of at least one rectangular opening is greater than or equal to the maximum demonstration height value H.

[0012] As an optional embodiment of this utility model, the width of each of the rectangular openings is equal, all satisfying W≤2σH / (ρgH) 2 -2σ).

[0013] As an optional embodiment of this utility model, the width value W of each rectangular opening is 2σH / (ρgH) 2 -2σ).

[0014] As an optional embodiment of this utility model, the width of each of the rectangular openings is not equal, and the maximum width satisfies W≤2σH / (ρgH). 2 -2σ).

[0015] As an optional embodiment of this utility model, the lengths of the long sides of the multiple rectangular openings are not equal.

[0016] As an optional embodiment of this utility model, the liquid container is a cylindrical liquid container, and the container chamber inside which the liquid is contained is a cylindrical chamber.

[0017] As an optional embodiment of this utility model, a liquid surface tension teaching demonstration tool of this utility model includes a tray, wherein the bottom of the liquid container is sealed to the upper surface of the tray, and together with the liquid container, they form a container chamber with an open top.

[0018] As an optional embodiment of this utility model, the liquid contained in the liquid container is liquid water, the preset maximum demonstration height value H = 0.05m, and the width value of the wide side of the rectangular opening W ≤ 0.2956cm.

[0019] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0020] Liquid surface tension is a result of intermolecular forces. If the width W of a rectangular opening is less than the width that the liquid surface tension can sustain, the liquid will be unable to overcome the surface tension and flow out of the rectangular opening. The liquid surface tension coefficient σ is the partial derivative of the Gibbs free energy G with respect to the area S, given constant temperature T and pressure P. According to physical principles, the surface tension at each liquid-gas interface is F. 单边=σcosθ·L, where L is the length of the corresponding side. Then the total surface tension of the liquid in the rectangular opening is F. 表面 =2σcosθ·H+2σcosθ·w.

[0021] Considering the container wall thickness, the liquid level is situated within a symmetrical rectangular opening. Under wetting conditions, when liquid-gas interfaces form on all four sides of the rectangular opening, the critical equilibrium condition ensuring the liquid remains stationary within container 1 is that the surface tension pressure difference equals the hydrostatic pressure, i.e. The solution yields the maximum width of the rectangular opening's widest side as W. max =2σH / (ρgH) 2 -2σ). Therefore, in order to ensure the success of the liquid surface tension teaching demonstration tool of this utility model, the width W of the rectangular opening satisfies: W≤2σH / (ρgH). 2 -2σ), the rectangular opening designed in this way can prevent liquid from flowing out even if it is submerged in the rectangular opening due to the surface tension of the liquid.

[0022] Furthermore, this utility model provides a teaching demonstration tool for liquid surface tension. By combining the phenomena of liquid surface tension and the barrel effect, multiple rectangular openings are made on the side wall of the liquid container, with at least one rectangular opening having a long side length greater than or equal to the maximum demonstration height H. Thus, before the width of the rectangular opening and the maximum demonstration height H reach a critical condition, the liquid will not flow out of the container through any of the rectangular openings, contradicting the barrel effect where the shortest stave determines the liquid level. In teaching activities, this tool can be used to conduct heuristic and exploratory scientific experiments, effectively stimulating students' desire for knowledge and achieving an edutainment effect. Attached image description:

[0023] Figure 1 This utility model provides a schematic diagram of the structure of a liquid surface tension teaching demonstration tool according to an embodiment;

[0024] Figure 2 This utility model provides a schematic diagram of the parameters of a liquid surface tension teaching demonstration tool. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model.

[0026] Therefore, the following detailed description of the embodiments of this utility model is not intended to limit the scope of the claimed utility model, but merely to illustrate some embodiments of the utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without inventive effort are within the scope of protection of this utility model.

[0027] It should be noted that, unless otherwise specified, the embodiments and features and technical solutions in the present invention can be combined with each other.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0029] In the description of this utility model, it should be noted that the terms "upper," "lower," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this utility model is in use, or the orientation or positional relationship commonly understood by those skilled in the art. These terms are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this utility model. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0030] See Figures 1-2 As shown in this embodiment, a liquid surface tension teaching demonstration tool includes:

[0031] Liquid container 1 has an internal chamber for holding liquid, and the liquid container 1 is made of a liquid-repellent material;

[0032] At least one rectangular opening (2, 3, 4) is formed on the side wall of the liquid container 1. The long side of the rectangular opening extends through the side wall along the vertical direction of the liquid container 1. The width W of the rectangular opening satisfies: W≤2σH / (ρgH) 2 -2σ), where σ is the surface tension coefficient of the liquid in the liquid container 1, ρ is the density of the liquid in the liquid container 1, g is the gravity coefficient, H is the preset maximum demonstration height value, and H represents the height at which the liquid in the liquid container 1 is higher than the bottom of the rectangular opening and remains in the liquid container 1 without flowing out of the rectangular opening.

[0033] Liquid surface tension is a result of intermolecular forces. If the width W of a rectangular opening is less than the width that the liquid surface tension can sustain, the liquid will be unable to overcome the surface tension and flow out of the rectangular opening. The liquid surface tension coefficient σ is the partial derivative of the Gibbs free energy G with respect to the area S, given constant temperature T and pressure P. According to physical principles, the surface tension at each liquid-gas interface is F. 单边 =σcosθ·L, where L is the length of the corresponding side. Then the total surface tension of the liquid in the rectangular opening is F. 表面 =2σcosθ·H+2σcosθ·w.

[0034] Considering the container wall thickness, the liquid level is situated within a symmetrical rectangular opening. Under wetting conditions, when liquid-gas interfaces form on all four sides of the rectangular opening, the critical equilibrium condition ensuring the liquid remains stationary within container 1 is that the surface tension pressure difference equals the hydrostatic pressure, i.e. The solution yields the maximum width of the rectangular opening's widest side as W. max =2σH / (ρgH) 2 -2σ). Therefore, in order to ensure the success of the liquid surface tension teaching demonstration tool in this embodiment, the width W of the rectangular opening satisfies: W≤2σH / (ρgH). 2 -2σ), the rectangular opening designed in this way can prevent liquid from flowing out even if it is submerged in the rectangular opening due to the surface tension of the liquid.

[0035] Furthermore, the liquid container 1 is made of a liquid-repellent material to avoid the failure of the liquid surface tension due to the hydrophilicity of the liquid container 1, which would result in a failed teaching demonstration. Specifically, the liquid container 1 in this embodiment can be made of glass.

[0036] Therefore, the liquid surface tension teaching demonstration tool of this embodiment has a simple structure, is easy to operate, has a high success rate, and can be reused repeatedly. In teaching activities, it can be used to carry out heuristic and exploratory scientific experiments, effectively stimulating students' desire for knowledge and achieving the effect of learning through play.

[0037] As an optional implementation of this embodiment, a rectangular opening is formed on the side wall of the liquid container 1, and the maximum demonstration height H is less than or equal to the length L of the longer side of the rectangular opening. Thus, when the height of the liquid in the liquid container 1 above the rectangular opening is less than or equal to the maximum demonstration height H, the liquid surface tension theory is satisfied, and the liquid cannot flow out of the rectangular opening. When the height of the liquid in the liquid container 1 above the rectangular opening is greater than the maximum demonstration height H, the liquid will flow out of the rectangular opening. This allows for a simple and intuitive demonstration of the liquid surface tension theory, and the demonstration results can be used for teaching.

[0038] As an optional implementation of this embodiment, multiple rectangular openings 2, 3, and 4 are formed on the side wall of the liquid container 1, and the length of the longer side of at least one rectangular opening is greater than or equal to the maximum demonstration height H. Thus, this embodiment of a liquid surface tension teaching demonstration tool can simultaneously conduct teaching demonstrations of the barrel theory.

[0039] The Cannikin's Law, also known as the barrel effect, states that the amount of water a barrel made of planks of varying lengths can hold depends not on the longest plank, but on the shortest. According to the Cannikin's Law, in this embodiment of the liquid surface tension demonstration tool, the liquid container 1 has multiple rectangular openings on its side wall. The maximum water level in the liquid container 1 should be at the lowest rectangular opening. However, because the rectangular openings in this embodiment satisfy the liquid surface tension theory, the water level in the liquid container 1 can exceed the lowest rectangular opening.

[0040] Therefore, this embodiment of a liquid surface tension teaching demonstration tool combines the phenomena of liquid surface tension and the barrel effect. Before the width of the rectangular opening and the maximum demonstration height H reach the critical conditions, the liquid will not flow out of the liquid container 1 through any rectangular opening, contradicting the barrel effect where the shortest stave determines the liquid level. In teaching activities, it can be used to conduct heuristic and exploratory scientific experiments, effectively stimulating students' desire for knowledge and achieving an edutainment effect.

[0041] Optionally, the width values ​​of the wide sides of each of the rectangular openings 2, 3, and 4 are equal, all satisfying W≤2σH / (ρgH) 2 -2σ).

[0042] Specifically, the width value W of the wide side of each of the rectangular openings 2, 3, and 4 is W = 2σH / (ρgH). 2 -2σ).

[0043] Optionally, the width of each of the rectangular openings is not equal, and the maximum width satisfies W≤2σH / (ρgH). 2 -2σ).

[0044] To more intuitively demonstrate the barrel effect, the lengths of the long sides of the rectangular openings 2, 3, and 4 described in this embodiment are not equal.

[0045] As an optional implementation of this embodiment, the liquid container 1 described in this embodiment is a cylindrical liquid container, and the container chamber inside which holds the liquid is a cylindrical chamber.

[0046] This embodiment provides a teaching demonstration tool for liquid surface tension, including a tray 5. The bottom of the liquid container 1 is sealed to the upper surface of the tray 5, together forming a container chamber with an open top.

[0047] As an optional implementation of this embodiment, this embodiment provides a liquid surface tension teaching demonstration tool. The liquid container 1 contains liquid water, the preset maximum demonstration height value H = 0.05m, and the width value W of the rectangular opening is ≤ 0.2956cm.

[0048] Taking liquid water as an example, according to publicly available information, the surface tension coefficient of pure water at 25℃ is 0.072 N / m, and its density is 1000 kg / m³. 3 g = 9.8 N / kg. Assuming the gap height is 0.05 m, substituting into the formula for calculating the width of the rectangular opening, we can calculate that the maximum gap width for maintaining liquid stillness due to the surface tension of pure water is approximately 0.2956 cm.

[0049] The above embodiments are only used to illustrate the present utility model and are not intended to limit the technical solutions described in the present utility model. Although the present utility model has been described in detail with reference to the above embodiments, the present utility model is not limited to the specific embodiments described above. Therefore, any modifications or equivalent substitutions to the present utility model, and all technical solutions and improvements that do not depart from the spirit and scope of the utility model, are covered within the scope of the claims of the present utility model.

Claims

1. A liquid surface tension teaching demonstration tool, characterized in that, include: A liquid container having an internal chamber for holding liquid, the liquid container being made of a liquid-repellent material; At least one rectangular opening is formed on the side wall of the liquid container, the longer side of the rectangular opening extending through the side wall along the vertical direction of the liquid container, and the width W of the rectangular opening satisfies: W≤2σH / (ρgH) 2 -2σ), where σ is the surface tension coefficient of the liquid in the liquid container, ρ is the density of the liquid in the liquid container, g is the gravity coefficient, H is the preset maximum demonstration height value, and H represents the height at which the liquid is above the bottom of the rectangular opening in the liquid container and remains inside the liquid container without flowing out of the rectangular opening.

2. A liquid surface tension teaching demonstration tool according to claim 1, wherein, A rectangular opening is formed on the side wall of the liquid container, and the maximum demonstration height value H is less than or equal to the length of the long side of the rectangular opening.

3. A liquid surface tension teaching demonstration tool according to claim 1, wherein, Multiple rectangular openings are formed on the side wall of the liquid container, and the length of the longer side of at least one rectangular opening is greater than or equal to the maximum demonstration height value H.

4. A liquid surface tension teaching demonstration tool according to claim 3, wherein, The width of the wide side of each of the rectangular openings is equal and satisfies W≤2σH / (ρgH 2 -2σ).

5. A liquid surface tension teaching demonstration tool according to claim 4, wherein, The width of the wide side of each of the rectangular openings is W = 2σH / (pgH 2 - 2σ).

6. A liquid surface tension teaching demonstration tool according to claim 3, wherein, The width of the wide side of each of the rectangular openings is not equal, the maximum width of the wide side satisfying W≤2σH / (ρgH 2 - 2σ).

7. A liquid surface tension teaching demonstration tool according to claim 3, wherein, The lengths of the long sides of the multiple rectangular openings are not equal.

8. A liquid surface tension teaching demonstration tool according to claim 1, wherein, The liquid container is a cylindrical liquid container, and the internal container chamber for holding the liquid is a cylindrical chamber.

9. A liquid surface tension teaching demonstration tool according to claim 1, wherein, Includes a tray, wherein the bottom of the liquid container is sealed to the upper surface of the tray, together forming a container chamber with an open top.

10. The liquid surface tension teaching demonstration tool of claim 1, wherein, The liquid container contains liquid water, the preset maximum demonstration height value H = 0.05m, and the width of the rectangular opening W ≤ 0.2956cm.

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