Demonstration device and demonstration method for magnetic susceptibility difference of different fluid substances in magnetic field

Abstract

The demonstration device comprises a support, a container supporting disc, a magnet disc, a powerful magnet, a supporting rod, an equipment support, a glass container and video recording equipment, the container supporting disc is installed on the upper portion of the support, and the glass container is arranged on the container supporting disc; multiple layers of magnet disc height adjusting supporting blocks are symmetrically arranged on the two sides of the lower portion of the support respectively, the magnet disc is erected on the two magnet disc height adjusting supporting blocks of any layer height, the powerful magnet is located below the glass container and installed on the magnet disc, and the bottom of the supporting rod is installed on one side of the support. One end of the device support is in threaded connection with the top of the supporting rod through a bolt and nut assembly I. The video recording device is installed at the other end of the device support. According to the invention, the paramagnetism and diamagnetism phenomena of different fluid substances can be effectively detected and analyzed, and a simple, visual and accurate means is provided for the research on the magnetic characteristics of the fluid substances.

Description

Technical Field

[0001] The invention belongs to the technical field of scientific and educational experimental instruments for electromagnetism, and specifically relates to a demonstration device and a demonstration method for the difference in magnetic susceptibility of different fluid substances in a magnetic field. Background Art

[0002] Magnetic susceptibility is one of the important parameters that characterize the magnetic properties of magnetic materials. A common method for measuring magnetic susceptibility is to use a vibrating sample magnetometer. The instrument is expensive and can only be operated by professionals in scientific research institutions. It is impossible to perceive changes in the state of magnetic materials during the experiment. Materials in a magnetic field will be magnetized by the magnetic field. Such materials that can be magnetized are magnetic media. According to the magnitude and properties of the additional magnetic induction intensity generated by the magnetic medium, it can be divided into paramagnetic materials and diamagnetic materials. For materials such as aluminum and manganese, the additional magnetic field is in the same direction as the original magnetic field, and they are called paramagnetic materials. For materials such as copper and bismuth, the additional magnetic field is in the opposite direction to the original magnetic field, and they are called diamagnetic materials. Since the additional magnetic field is much smaller than the original magnetic field, the effect on the original magnetic field is very small. Paramagnetic materials and diamagnetic materials are also collectively referred to as weakly magnetic materials. Currently, professional laboratories in universities often use the Gouy magnetic balance device to indirectly measure the magnetic susceptibility of materials by detecting the weight gain of materials in a gradient magnetic field. The experimental principle of the Gouy method for determining the magnetic susceptibility of materials is as follows: Figure 4 As shown in the figure, the experiment of measuring the magnetic susceptibility of a substance by the Gouy method is to hang a flat-bottomed glass tube containing a sample at one end of a balance, with the bottom of the sample at the center of the two poles of the electromagnet, where the magnetic field strength is the strongest, and the other end of the sample at a position where the magnetic field strength is negligible. The instrument includes an electromagnet, a constant current power supply, a CT5 gaussmeter, an instrument switch, a lighting system water cooling system, and an integral frame. The Gouy magnetic balance device can be used to obtain the magnetic susceptibility value of the sample, but it cannot intuitively display the property differences and phenomena of paramagnetic and diamagnetic materials in a magnetic field. Summary of the invention

[0003] In view of the problems existing in the above-mentioned prior art, the present invention provides a demonstration device and a demonstration method for the difference in magnetic susceptibility of different fluid materials in a magnetic field, with the aim of effectively detecting and analyzing the paramagnetism and diamagnetic phenomena of different fluid materials, thereby providing a simple, intuitive and accurate means for studying the magnetic properties of fluid materials.

[0004] In order to achieve the above object, the specific scheme of the present invention is as follows:

[0005] A demonstration device for demonstrating the difference in magnetic susceptibility of different fluid substances in a magnetic field comprises a bracket, a container support plate, a magnet plate, a strong magnet, a support rod, an equipment bracket, a glass container for loading fluid substances and a video recording device for recording the change in magnetic susceptibility of the fluid substance in a magnetic field, wherein the container support plate is installed on the upper part of the bracket, the glass container is arranged on the container support plate, multiple layers of magnet plate height adjustment support blocks are symmetrically arranged on both sides of the lower part of the bracket, the magnet plate is mounted on two magnet plate height adjustment support blocks of arbitrary layer heights, the strong magnet is located below the glass container and is mounted on the magnet plate, the bottom of the support rod is installed on one side of the bracket, one end of the equipment bracket is threadedly connected to the top of the support rod through a bolt and nut assembly, and the video recording device is installed on the other end of the equipment bracket.

[0006] Furthermore, the strong magnet is a neodymium iron boron magnet, and the video recording device is a mobile phone, a camera or a camcorder.

[0007] Furthermore, it includes a pen clip, a laser pen, a projection screen and a gaussmeter, wherein the pen clip is threadedly connected to the support rod through a bolt and a nut assembly, the laser pen is clamped on the pen clip, and the laser beam emitted by the laser pen is aimed at the glass container, the projection screen is set on the side opposite to the laser pen, and the probe of the gaussmeter is placed at the position where the strong magnet generates a magnetic field.

[0008] Furthermore, the projection screen is a wall, a soft screen or a hard screen, the soft screen is a white plastic screen, a pearlescent screen or a metal screen, and the hard screen is a glass screen.

[0009] Furthermore, it is characterized in that universal wheels with brakes are provided on both sides of the bottom of the bracket.

[0010] The method for demonstrating the change of magnetic susceptibility using the device comprises the following steps:

[0011] Lay grid paper between the glass container and the container support plate, place a strong magnet on the magnet plate and directly below the glass container, put paramagnetic fluid and diamagnetic fluid respectively in the glass container, turn on the video recording equipment to record the changes of grid pattern of the grid paper under the same magnetic field for the paramagnetic fluid and diamagnetic fluid respectively, and intuitively display the property differences and phenomena of the paramagnetic fluid and diamagnetic fluid in the magnetic field according to the changes of the grid pattern, place the magnet plate on magnet plate height adjustment support blocks with different heights, change the magnetic induction intensity of the glass container containing the fluid material by adjusting the distance between the strong magnet and the glass container, so as to intuitively display the changes of the grid pattern, and obtain the magnitude of the magnetic induction intensity in the magnetic field by measuring with a gaussmeter.

[0012] Furthermore, the paramagnetic fluid is a manganese chloride solution, and the diamagnetic fluid is water.

[0013] The method for demonstrating the change of magnetic susceptibility using the device comprises the following steps:

[0014] Turn on the laser pen and adjust the angle of the laser pen so that the laser spot emitted by the laser pen is located in the central area of ​​the glass container. Receive the reflected laser spot through the projection screen, and use the video recording device to record the height of the laser spot to the water surface when no strong magnet is placed. Then, after adding the strong magnet, record the changed angle between the incident light of the laser pen and the water surface, the changed angle of the reflected light, and the height of the laser spot on the projection screen. Through the change in the height of the laser spot on the projection screen, compare the shape changes, magnetic susceptibility and property differences of different fluid substances under the same magnetic field.

[0015] Advantages of the present invention

[0016] The present invention discloses a demonstration device and a demonstration method for demonstrating the difference in magnetic susceptibility of different fluid materials in a magnetic field. The device is a scientific and educational instrument for intuitive demonstration. The device can effectively detect and analyze the paramagnetism and diamagnetic phenomena of different fluid materials, and provides a simple, intuitive and accurate means for studying the magnetic properties of fluid materials. The present invention is mainly used as a scientific instrument in primary and secondary schools and science museums. The device has a simple structure and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the demonstration device of the present invention.

[0018] Figure 2 Schematic diagram of the surface shape change of paramagnetic fluid and diamagnetic fluid in the glass container of Experiment 1 in a magnetic field and in the absence of a magnetic field. Among them, (a) is a grid paper state display diagram of water in the absence of a magnetic field; (b) is a grid paper state diagram of water in a magnetic field; (c) is a grid paper state diagram of manganese chloride in a magnetic field.

[0019] Figure 3 This is a graph showing the change in liquid surface height of the aqueous solution under laser irradiation in Experiment 3 with or without an external magnetic field.

[0020] Figure 4 This is the experimental principle of the Gouache method in the prior art for determining the magnetic susceptibility of a material.

[0021] Figures 1 to 3 middle:

[0022] 1. Bracket; 2. Container support plate; 3. Magnet plate; 4. Strong magnet; 5. Support rod; 6. Equipment bracket; 7. Glass container; 8. Magnet plate height adjustment support block; 9. Video recording equipment; 10. Gauss meter; 11. Bolt and nut assembly one; 12. Grid paper; 13. Pen clip; 14. Laser pen; 15. Projection screen; 16. Bolt and nut assembly two; 17. Fluid material; 18. Universal wheel with brake.

[0023] Figure 4 middle:

[0024] 19. Electronic balance; 20. Glass tube; 21. Liquid; 22. Electromagnet. DETAILED DESCRIPTION

[0025] The present invention is further explained and illustrated below in conjunction with the accompanying drawings and specific embodiments. It should be noted that this specific embodiment is not intended to limit the scope of rights of the present invention.

[0026] When studying the behavior of the fluid material 17 in a magnetic field, its magnetic properties are determined by observing the shape changes on the surface of the fluid material 17. Figure 2 As shown, the diamagnetic fluid moves to the outer edge of the magnet, where the magnetic field is weaker, forming a concave shape. The paramagnetic fluid is attracted to the center of the magnet in the area with the strongest magnetic field, and the liquid surface rises above the magnet, forming a convex shape. Because the magnetic susceptibility of the fluid substance 17 sample is too small, the attraction or repulsion of the fluid substance 17 in the magnetic field is very weak, making it difficult to detect and analyze intuitively.

[0027] Therefore, if Figure 1 As shown, this embodiment provides a demonstration device for the difference in magnetic susceptibility of different fluid substances in a magnetic field, including a bracket 1, a container support plate 2, a magnet plate 3, a strong magnet 4, a support rod 5, an equipment bracket 6, a grid paper 12, a pen clip 13, a laser pen 14, a projection screen 15, a glass container 7 for loading fluid substances, and a video recording device 8 for recording the change in magnetic susceptibility of the fluid substance 17 in the magnetic field.

[0028] The container support plate 2 is mounted on the upper part of the bracket 1, and the glass container 7 is arranged on the container support plate 2. The glass container 7 is used to hold a fluid sample. The transparent glass container is helpful to observe the changes on the surface of the fluid sample through light.

[0029] The grid paper 12 is arranged between the glass container 7 and the container support plate 2. The specifications of the grid paper 12 can be selected from 1mm grid paper or 0.5mm grid paper. The grid size of the 1mm grid paper is 1mm, and the line spacing is 1mm; the grid size of the 0.5mm grid paper is 0.5mm, and the line spacing is 0.5mm. The grid paper 12 is used to assist in observing the changes on the surface of the fluid material. The grid size and line spacing of the grid paper 12 can help to more intuitively measure the deformation degree of the surface of the fluid material.

[0030] The lower sides of the bracket 1 are symmetrically provided with multi-layer magnet disk height adjustment support blocks 8, the magnet disk 3 is mounted on two magnet disk height adjustment support blocks 8 of any layer height, the strong magnet 4 is located below the glass container 7 and is installed on the magnet disk 3, the strong magnet 4 is a neodymium iron boron magnet, the strong magnet 4 is used to generate a magnetic field, and the strength and shape of the strong magnet affect the distribution of the magnetic field, thereby affecting the reaction of the fluid substance. The strength of the magnetic field can be changed by adjusting the distance between the strong magnet 4 and the glass container 6, because the magnetic induction intensity excited by the strong magnet 4 decreases with the increase of the distance in the surrounding space, so by adjusting the different distances from the strong magnet 4 to the glass container 6, magnetic fields of different strengths can be formed.

[0031] The bottom of the support rod 5 is installed on one side of the bracket 1, and one end of the equipment bracket 6 is clamped on the support rod 5 and is threadedly connected to the top of the support rod 5 through a bolt and nut assembly 11. The function of the bolt and nut assembly 11 is to facilitate the adjustment of the up and down angles of the equipment bracket 6 so as to record and observe the changes in the grid pattern of the grid paper in the glass container. The video recording device 9 is installed at the other end of the equipment bracket 6.

[0032] The video recording device 9 is a mobile phone, a camera or a video camera. The video recording device 9 is used to record the experimental phenomenon for subsequent analysis and comparison. A camera or a mobile phone is used to shoot the surface of the fluid material 17 and the grid pattern in the grid paper.

[0033] The pen clip 13 is clamped on the support rod 5 and is threadedly connected to the support rod 5 through the bolt and nut assembly 16. The laser beam emitted by the laser pen 2 is aimed at the glass container 6. The bolt and nut assembly 16 is used to facilitate the pen clip 13 to adjust the angle. Universal wheels 18 with brakes are also set on both sides of the bottom of the bracket 1 to facilitate the movement of the bracket 1 to adjust the projection distance between the laser pen 14 and the projection screen 15. The projection screen 15 is set on the side opposite to the laser pen 14, and the probe of the gauss meter 10 is placed at the position where the strong magnet 4 generates a magnetic field. The projection screen 15 is a wall, a soft screen or a hard screen. The soft screen is a white plastic screen, a pearlescent screen or a metal screen, and the hard screen is a glass screen. The projection screen 15 is set on the side opposite to the laser pen 14.

[0034] The probe of the Gaussmeter 10 is placed at different positions where the strong magnet 4 generates a magnetic field, so as to measure the magnetic field strength of the strong magnet 4 in different spaces in real time. The Gaussmeter 10 is a millitesla meter of the Gaozhi Precision brand, which is used to measure the static or dynamic (AC) magnetic induction strength of a fluid material 17 at a point in space. The Hall sensor or fluxgate sensor of the millitesla meter passes through the magnetic field lines of the fluid material 17 to generate current and voltage, and the magnetic induction strength is displayed on the millitesla meter display.

[0035] The method for demonstrating the change of magnetic susceptibility using the above device comprises the following steps:

[0036] The grid paper 12 is laid between the glass container 7 and the container support plate 2, and the strong magnet 4 is placed on the magnet plate 3 and is located directly below the glass container 7. A paramagnetic fluid and a diamagnetic fluid are placed in the glass container 7 respectively. The paramagnetic fluid in this embodiment is a manganese chloride solution, and the diamagnetic fluid is water. The video recording device 9 is turned on to record the grid pattern changes of the grid paper 12 of the paramagnetic fluid and the diamagnetic fluid in the same magnetic field. The property differences and phenomena of the paramagnetic fluid and the diamagnetic fluid in the magnetic field are visually displayed according to the changes in the grid pattern. The magnet plate 3 is placed on the magnet plate height adjustment support block 8 of different layer heights. The magnetic induction intensity of the glass container 7 containing the fluid substance 17 is changed by adjusting the distance between the strong magnet 4 and the glass container 7 to visually display the grid pattern changes of the grid paper 12. The magnitude of the magnetic induction intensity in the magnetic field is measured by the gauss meter 10.

[0037] The method for demonstrating the change of magnetic susceptibility using the above device comprises the following steps:

[0038] The laser pen 14 is turned on, and the angle of the laser pen 14 is adjusted so that the laser spot emitted by the laser pen 14 is located in the central area of ​​the glass container 7. The reflected laser spot is received by the projection screen 15. The height of the laser spot to the water surface when the strong magnet 4 is not placed is recorded by the video recording device 9. Then, after the strong magnet 4 is added, the angle between the incident light of the laser pen and the water surface, the angle change of the reflected light, and the height of the laser spot on the projection screen are recorded. Through the height change of the laser spot on the projection screen 15, the shape change, magnetic susceptibility and property difference of different fluid substances 17 under the same magnetic field are compared. The magnetic induction intensity in the magnetic field is measured by the gauss meter 10.

[0039] Experiment 1: Differences in paramagnetism and diamagnetic phenomena of different fluid substances

[0040] According to the experimental requirements, a fluid sample 18 of a diamagnetic fluid and a paramagnetic fluid is placed in a glass container 7. The diamagnetic fluid is water, and the paramagnetic fluid is a manganese chloride solution.

[0041] Experiment 1 Phenomenon Description:

[0042] 1. When no magnet is placed: the diamagnetic fluid in the glass container 7 is water in a static state, with a flat surface and a flat grid image without deformation. At this time, the diamagnetic fluid is only affected by gravity and is not affected by the magnetic field.

[0043] 2. When inserting the magnet:

[0044] Paramagnetic fluid: Under the action of the magnetic field, the paramagnetic fluid is manganese chloride solution, which is attracted to the strongest magnetic field area at the center of the strong magnet 4, and the liquid surface rises to form a convex shape. At this time, the image of the grid paper 12 will be deformed, and the grid lines will gather toward the center in the convex area on the surface of the paramagnetic fluid, and the grid spacing will become smaller, while in the area far away from the center of the strong magnet 4, the grid spacing is relatively large.

[0045] Diamagnetic fluid: Under the action of the magnetic field, the diamagnetic fluid is water which is repelled to the weak magnetic field area at the outer edge of the strong magnet, and the liquid surface is concave, forming a concave shape. At this time, the grid paper image will also be deformed, and the grid lines will spread outward in the concave area of ​​the diamagnetic fluid surface, and the grid spacing will become larger, while in the area close to the center of the strong magnet 4, the grid spacing is relatively small.

[0046] Experiment 1 Observation and recording methods:

[0047] 1. Observation with naked eyes: During the experiment, when the fluid substance 17 placed in the magnetic field is subjected to the external magnetic field, the surface shape of the fluid substance 17 will change, but this change is very small and difficult to be directly observed with the naked eye. Therefore, by placing a grid paper under the glass container 7, the deformation of the grid pattern of the grid paper 12 is observed at the same time for the same fluid substance 17 in two different states: in the magnetic field and without the magnetic field.

[0048] 2. Video recording equipment recording: Using a camera or mobile phone to take images of the surface of the fluid material 17 and the grid paper can record the experimental phenomena more clearly. By comparing the images of different fluid materials 17 in the magnetic field, their magnetic properties can be analyzed more intuitively. In addition, the captured images can also be used for subsequent image processing and analysis, such as calculating the degree of deformation of the fluid surface, drawing the contour curve of the surface of the fluid material 17, etc., so as to obtain more accurate experimental data and conclusions.

[0049] By observing the behavior of the fluid material 17 in the magnetic field, its magnetic properties can be preliminarily determined. However, since the magnetic susceptibility of the fluid material 17 is small, the attraction or repulsion of the magnetic field on it is weak, so it is necessary to use the experimental device and recording method of this embodiment to amplify and clearly observe these phenomena. By comparing the performance of different fluids in the magnetic field, their magnetic properties and their behavior laws in the magnetic field can be better understood.

[0050] Experiment 2: Experimental phenomena of different fluid substances in magnetic field

[0051] A glass container with a radius of 45 mm and a height of 15 mm is used so that the image of the grid can be observed on the surface of the fluid substance 17 and it is ensured that the bottom of the glass container 7 is filled with the fluid substance 17 .

[0052] Experimental conditions for Test 2:

[0053] According to the volume of the fluid substance 17, the magnetic induction intensity B at the position of the fluid substance 17 is less than 400 mT.

[0054] Different volumes are used, the reverse magnetic fluid is water, and the paramagnetic fluid is manganese chloride solution. The volume of the aqueous solution is about 10 ml, and the volume of the manganese chloride aqueous solution is about 50 ml.

[0055] Experiment 2 Phenomenon Description:

[0056] 1. No magnet state: When no strong magnet 4 is placed under the fluid substance 17, the image appearing on the liquid surface of the fluid substance 17 is similar to the image formed by a plane mirror, and the grid pattern will not be deformed.

[0057] 2. Add water:

[0058] After moving the strong magnet 4, the observed pattern bends toward the magnet, and the grid image in the center is deformed to form an extended grid image. This is because the diamagnetic liquid is repelled to the area with weaker magnetic field, and the liquid surface is concave. If other diamagnetic fluid substances are put in, the extended grid image will also appear.

[0059] 3. Add manganese chloride solution:

[0060] After moving the strong magnet 4, the observed pattern bends towards the magnet, forming an image with a contracted center. This is because the paramagnetic liquid is attracted to the area with the strongest magnetic field, and the liquid surface bulges.

[0061] This experiment 2 can detect the deformation of the liquid surface of a fluid substance 17 less than 50μm through optical phenomena, with high sensitivity and accuracy. Under different magnetic field environments, the phenomena of different fluid substances 17 are significantly different, which intuitively shows the properties of the fluid substance 17 and is easy to observe and analyze. The image magnification method is used to amplify the differences in the reflected patterns to further improve the accuracy of observation and analysis. Detection and analysis can be carried out by naked eye observation or photographic recording, without the need for complex instruments and equipment. The device is suitable for the detection of a variety of fluid substances 17, including fluids with different magnetic properties such as water and manganese chloride solution.

[0062] Experiment 3: Display of the magnetic susceptibility of paramagnetic or diamagnetic materials

[0063] For paramagnetic or diamagnetic materials, the magnetic susceptibility of different fluid materials is different, indicating the difference in magnetic properties of different fluid materials. The magnetic susceptibility of different fluid materials intuitively shows the size difference.

[0064] Fill the glass container 7 with water, and place the strong magnet 4 on the magnet plate height adjustment support block 6 of suitable height. After determining the position of the strong magnet 4, use the pen clip 13 to install the laser pen 14 on the bracket 1, and adjust the angle through the laser pen 14 so that the laser emitted by the laser pen 14 can be emitted to the center point area of ​​the glass container 7, ensuring that the laser spot is located in the center area of ​​the magnetic field. In this experiment 3, the wall is selected as the projection screen 15 for receiving the reflected laser spot. The projection screen 15 is set on the side opposite to the laser pen 14, and the distance from the glass container 7 to the wall is X meters.

[0065] Without the strong magnet 4, the height of the laser spot from the water surface is Y1 meters. After the strong magnet 4 is added, the water surface is deformed and has a concave shape, the angle between the incident light and the water surface changes by θ, the reflection angle of the reflected light changes by 2θ, and the height of the laser spot from the wall changes by Y2.

[0066] Through the analysis of geometric optics, the change of liquid surface height and the influence of external magnetic field can be sensitively displayed, the subtle change of water surface height can be amplified, and the difference of magnetic susceptibility of fluid samples can be directly indicated.

[0067] Specifically, a glass container 6 with a diameter of 10 cm is used, which is filled with water to a depth of about 0.5 cm. A round strong magnet 4 with a diameter of 4 cm is selected and placed on a magnet plate height adjustment support block 6 of a suitable height. The laser pen 14 is mounted on a support rod 5 15 cm above the glass container 7, and the angle of the laser pen 14 is adjusted so that the laser emission of the laser pen 14 is aimed at the water in the center of the glass container 6, and the angle with the horizontal plane is about 30°. The bracket 1 is moved so that the bracket 1 is X meters away from the wall to ensure that the reflected laser beam is observed on the wall.

[0068] like Figure 3 As shown, the distance x=5m between the laser spot on the water surface and the wall is measured. In the absence of a magnetic field, the height difference between the laser spot reflected on the water surface and the wall is y=1.2m. When the water surface is deformed by the magnetic field, the change in the slope of the water surface causes the incident angle of the laser on the water to change by Δθ, which further causes the angle of the reflected beam to change by 2Δθ with the original beam, and finally the reflected laser forms a height change of Δy on the wall.

[0069]

[0070] By comparing the shape changes of different fluid substances 17 under the same magnetic field and the height change Δy of the laser spot on the wall, the magnetic susceptibility and property differences of different fluid substances 17 can be directly compared.

[0071] The above device compares the size of Δy1 and Δy2 through the height change difference of the laser reflection spot to determine the difference in magnetic susceptibility when the fluid material 17 is water and when the fluid material 17 is manganese chloride solution.

Claims

1. A demonstration device for demonstrating the difference in magnetic susceptibility of different fluid materials in a magnetic field, characterized in that: It includes a bracket, a container support plate, a magnet plate, a strong magnet, a support rod, an equipment bracket, a glass container for loading fluid substances and a video recording device for recording changes in the magnetic susceptibility of the fluid substances in a magnetic field. The container support plate is installed on the upper part of the bracket, and the glass container is arranged on the container support plate. Both sides of the lower part of the bracket are symmetrically provided with multi-layer magnet plate height adjustment support blocks, and the magnet plate is mounted on two magnet plate height adjustment support blocks of arbitrary layer heights. The strong magnet is located below the glass container and is installed on the magnet plate. The bottom of the support rod is installed on one side of the bracket. One end of the equipment bracket is threadedly connected to the top of the support rod through a bolt and nut assembly, and the video recording device is installed on the other end of the equipment bracket.

2. The device according to claim 1, characterized in that The invention comprises a grid paper which is arranged between the glass container and the container support plate.

3. The device according to claim 1, characterized in that A gaussmeter is included, the probe of which is placed at a location where a strong magnet generates a magnetic field.

4. The device according to claim 1, characterized in that The strong magnet is a neodymium iron boron magnet, and the video recording device is a mobile phone, a camera or a camcorder.

5. The device according to claim 1, characterized in that The invention comprises a pen clip, a laser pen and a projection screen. The pen clip is threadedly connected to a support rod through a bolt and a nut assembly. The laser pen is clamped on the pen clip, and the emitted laser beam of the laser pen is aimed at the glass container. The projection screen is arranged on the side opposite to the laser pen.

6. The device according to claim 3, characterized in that The projection screen is a wall, a soft screen or a hard screen, the soft screen is a white plastic screen, a pearlescent screen or a metal screen, and the hard screen is a glass screen.

7. The device according to claim 1, characterized in that Universal wheels with brakes are also arranged on both sides of the bottom of the bracket.

8. A method for demonstrating magnetic susceptibility change using the device of claim 1, 2, 3 or 4, characterized in that: The following steps are involved: Lay the grid paper between the glass container and the container support plate, and place a strong magnet on the magnet plate and directly below the glass container, put a paramagnetic fluid and a diamagnetic fluid in the glass container respectively, turn on the video recording equipment to record the changes of the grid pattern of the grid paper of the paramagnetic fluid and the diamagnetic fluid in the same magnetic field respectively, and intuitively display the property differences and phenomena of the paramagnetic fluid and the diamagnetic fluid in the magnetic field according to the changes of the grid pattern, place the magnet plate on the magnet plate height adjustment support blocks with different layer heights, change the magnetic induction intensity of the glass container containing the fluid material by adjusting the distance between the strong magnet and the glass container, so as to intuitively display the changes of the grid pattern, and obtain the magnitude of the magnetic induction intensity in the magnetic field by measuring with a gaussmeter.

9. The method according to claim 8, characterized in that: The paramagnetic fluid is manganese chloride solution, and the diamagnetic fluid is water.

10. A method for demonstrating magnetic susceptibility change using the device of claim 1, 3, 4, 5 or 6, characterized in that: The following steps are involved: Turn on the laser pen and adjust the angle of the laser pen so that the laser spot emitted by the laser pen is located in the central area of ​​the glass container. Receive the reflected laser spot through the projection screen, and use a video recording device to record the height of the laser spot to the water surface when no strong magnet is placed. Then, after adding a strong magnet, record the changed angle between the incident light of the laser pen and the water surface, the changed angle of reflected light, and the height of the laser spot on the projection screen. Through the change in the height of the laser spot on the projection screen, compare the shape changes, magnetic susceptibility and property differences of different fluid substances under the same magnetic field, and obtain the magnetic induction intensity in the magnetic field by measuring with a gaussmeter.

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