Standing wave demonstration instrument

Abstract

According to the standing wave demonstration instrument, a motor serves as a vibration source, a photoelectric speed measurement coded disc with an eccentric shaft is installed on a rotating shaft of the motor, the rotating motion of the motor is converted into vertical vibration of a vibration rod, so that string vibration is driven, after waves generated by vibration are reflected, the two waves are superposed, and after certain conditions are met, the standing wave phenomenon is generated. Compared with a traditional electromagnetic oscillation mode, the mode of generating string vibration through mechanical driving can increase the amplitude of string vibration, so that a more obvious standing wave phenomenon is displayed, and students can observe and understand standing wave characteristics more easily. And the chord line adopts the sidelight visible optical fiber, and the visual effect can be enhanced by matching with the light source. After the light source is electrified, the light source irradiates the chord line, the chord line emits light, the standing wave phenomenon can be observed by observing the light-emitting chord line without the help of an oscilloscope, standing wave visualization is achieved, and the structure of the standing wave demonstration instrument is simplified.

Description

Technical Field

[0001] The invention relates to the technical field of standing wave exploration, and in particular to a standing wave demonstrator. Background Art

[0002] Standing waves are a special interference phenomenon. When two waves that meet the conditions of equal amplitude, same vibration direction, same frequency, and fixed phase difference propagate in opposite directions, the special interference phenomenon produced by the superposition of the two waves is called standing waves. In standing waves, the points on the string that are always stationary are called nodes, and the points between nodes with the largest amplitude are called antinodes.

[0003] The standing wave phenomenon usually needs to be demonstrated with the help of a standing wave demonstrator. Most of the existing standing wave demonstrator generate string vibration signals through electromagnetic oscillation. The wave amplitude generated by this method is small, which is not conducive to students observing the standing wave phenomenon. In addition, the structure is relatively complex and the cost is high, which is not convenient for teachers or students to make it by themselves. In addition, when observing standing waves, the existing standing wave demonstrator needs to use an oscilloscope to observe the standing wave phenomenon more clearly. This method is not intuitive and interesting, the visual effect is poor, and it is not convenient for observing the nodes and antinodes, which is not conducive to students understanding the characteristics of standing waves. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a standing wave demonstrator to solve the problems that the existing standing wave demonstrator has a complex structure, the amplitude of the generated wave is small, which is not conducive to students observing the standing wave phenomenon, and an oscilloscope is needed to observe the standing wave phenomenon more clearly, the phenomenon is not intuitive enough, the visual effect is poor, and it is not convenient to observe the nodes and antinodes, which is not conducive to students understanding the characteristics of the standing wave.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: A standing wave demonstrator comprises a base, one end of which is provided with an electrically connected motor and a motor speed regulating device, and the other end is provided with a fixed pulley; a speed measuring code disk with an eccentric shaft is provided on the rotating shaft of the motor, a vibration rod is provided on the eccentric shaft parallel to the speed measuring code disk, one end of the vibration rod is provided with a first slide groove along the length direction of the vibration rod, the eccentric shaft passes through the first slide groove and can slide in the first slide groove; a support frame is provided on the end of the base close to the motor between the motor and the fixed pulley, a fixed shaft is provided on the support frame, the middle part of the vibration rod is sleeved on the fixed shaft and can rotate around the fixed shaft; the other end of the vibration rod is fixed to one end of the string, the middle part of the string passes around the fixed pulley, and the other end is connected with a weight to make the string in a straight state; a support block is provided on the base directly below the string, the string can just be pressed on the top of the support block, and the string between the support block and the vibration rod is parallel to the base; the height of the fixed pulley is lower than the height of the support block.

[0006] Furthermore, a hanging ring is fixed to one end of the string close to the weight, and the weight is hung on the hanging ring.

[0007] Furthermore, the string is a side-light visible optical fiber, and a light source is fixed to one end of the string close to the weight. When the light source is powered on, the light emitted is directed directly to the string, making the string glow.

[0008] Furthermore, a second slide groove is provided on the upper surface of the base, directly below the string line and parallel to the string line, and the bottom of the support block extends into the second slide groove and can slide along the second slide groove.

[0009] Furthermore, a scale is provided on the base parallel to the string line to facilitate measurement of the length of the string line.

[0010] Furthermore, a straight laser pen which can slide parallel to the string is fixed above the string, and the laser emitted by the straight laser pen is facing the string.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1. The standing wave demonstrator of the present invention uses a motor as a vibration source, and installs a photoelectric speed measuring code disk with an eccentric shaft on the rotating shaft of the motor, converting the rotational motion of the motor into the up and down vibration of the vibration rod, thereby driving the string vibration. Compared with the traditional electromagnetic oscillation method, this mechanical drive method of generating string vibration can increase the amplitude of the string vibration, thereby showing a more obvious standing wave phenomenon, which is more conducive to students observing and understanding the standing wave characteristics.

[0012] 2. The string of the present invention adopts side-light visible optical fiber, which can enhance the visual effect when matched with a light source. After the light source is powered on, it shines on the string, and the string itself emits light. By observing the glowing string, the standing wave phenomenon can be observed without the aid of an oscilloscope, which realizes the visualization of the standing wave and simplifies the structure of the standing wave demonstrator.

[0013] 3. The present invention sets a straight laser pen above the string line that can move parallel to the string line. The position of the string line can be accurately located by laser irradiation, which is convenient for accurately measuring the length of the string line. The laser pen can also accurately locate the wave nodes and wave antinodes, which is convenient for students to distinguish wave nodes and wave antinodes and further understand the characteristics of standing waves. In addition, the standing wave demonstrator of the present invention has a simple structure, is easy to install and debug, and is easy to promote and apply. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of the standing wave demonstrator of the present invention; Figure 2 This is an experimental effect diagram of the standing wave phenomenon demonstrated by the standing wave demonstrator of the present invention; Figure 3 This is an experimental diagram of the laser pen of the present invention measuring the length of a string; Figure 4 It is a comparison diagram of the standing wave phenomenon under different parameters when the standing wave demonstrator of the present invention is used for demonstration.

[0015] In the figure, a base 1, a motor 2, a motor speed regulating device 3, a fixed pulley 4, a photoelectric speed measuring code disc 5, an eccentric shaft 6, a vibration rod 7, a first slide 8, a support frame 9, a fixed shaft 10, a string 11, a weight 12, a support block 13, a light source 14, a second slide 15, a scale 16, a single-word laser pen 17, a hanging ring 18, a background plate 19, a third slide 20, and a fixed frame 21. DETAILED DESCRIPTION

[0016] The specific implementation of the present invention is further described in detail below in conjunction with specific embodiments and drawings. Example

[0017] like Figure 1As shown, a standing wave demonstrator comprises a base 1, one end of which is provided with an electrically connected motor 2 and a motor speed regulating device 3, and the other end of which is provided with a fixed pulley 4; a photoelectric speed measuring code disc 5 with an eccentric shaft 6 is installed on the rotating shaft of the motor 2, a vibration rod 7 is installed on the eccentric shaft 6 parallel to the photoelectric speed measuring code disc 5, one end of the vibration rod 7 is provided with a first slide groove 8 along the length direction of the vibration rod 7, the eccentric shaft 6 passes through the first slide groove 8 and can slide in the first slide groove 8; a support frame 9 is provided on the end of the base 1 between the motor 2 and the fixed pulley 4 close to the motor 2 A fixed shaft 10 is provided on the support frame 9, and the middle part of the vibration rod 7 is sleeved on the fixed shaft 10 and can rotate around the fixed shaft 10; the other end of the vibration rod 7 is fixed to one end of the string 11, the middle part of the string 11 passes around the fixed pulley 4, and the other end is hung with a weight 12 to keep the string 11 in a straight state; a support block 13 is provided on the base 1 just below the string 11, and the string 11 can just be pressed on the top of the support block 13, and the string 11 between the support block 13 and the vibration rod 7 is parallel to the base 1; the height of the fixed pulley 4 is lower than the height of the support block 13.

[0018] In specific implementation, a hanging ring 18 is fixed to one end of the string 11 close to the weight 12, and the weight 12 is hung on the hanging ring 18. In this way, the tension of the string 11 can be adjusted by increasing or decreasing the number of weights 12 on the hanging ring 18, which is conducive to students exploring the relationship between standing waves and string tension.

[0019] In a specific implementation, the string 11 is a side-light visible optical fiber, and an LED light source 14 is fixed to one end of the string 11 near the weight 12. When the LED light source 14 is powered on, the light emitted is directed directly to the string 11, making the string 11 glow. The string 11 is made of a side-light visible optical fiber material and is equipped with an LED light source 14. When the LED light source 14 is powered on, the string 11 itself can glow, so that students can directly observe the standing wave phenomenon without the need for an oscilloscope. The phenomenon is more intuitive and interesting, which is conducive to students understanding the characteristics of standing waves.

[0020] During specific implementation, the hanging ring 18 can be fixed on the bottom of the light source 14 , or on the string 11 above the light source 14 .

[0021] In a specific implementation, a second slide groove 15 is provided on the upper surface of the base 1 directly below the string 11 and parallel to the string 11, and the bottom of the support block 13 extends into the second slide groove 15 and can slide along the second slide groove 15. In this way, the length of the string 11 can be adjusted by sliding the support block 13, so as to qualitatively study the relationship between the standing wave and the length of the string 11.

[0022] In specific implementation, a scale 16 is provided on the base 1 parallel to the string 11 to facilitate measuring the length of the string 11. This can facilitate recording the length of the string 11 during different standing wave phenomena, providing data reference for subsequent standing wave demonstration experiments, so as to facilitate quick and intuitive demonstration of the standing wave phenomenon.

[0023] In specific implementation, a vertically arranged background plate 19 is installed on the upper surface of the base 1 parallel to the string line 11, and a third slide groove 20 is provided at the upper end of the background plate 19 along the length direction of the background plate 19, and a fixing frame 21 which can slide in the third slide groove 20 is installed in the third slide groove 20, and a straight laser pen 17 is installed on the fixing frame 21, and the straight laser pen 17 is just suspended above the string line 11, and the laser it emits is facing the string line 11. The pattern illuminated by the straight laser pen 17 is in the shape of a straight line, which is convenient for reading the length of the string line 11 and making the measurement more accurate. At the same time, by sliding the straight laser pen 17 to illuminate the nodes and antinodes, students can more intuitively distinguish the nodes and antinodes and further understand the characteristics of standing waves.

[0024] Working principle: When performing a standing wave demonstration, after the motor, photoelectric speed code disk and light source are powered on, the motor rotates to drive the photoelectric speed code disk to rotate. The eccentric shaft on the photoelectric speed code disk drives the vibration rod to vibrate up and down, thereby driving the string to vibrate, forming a one-dimensional transverse wave. The wave propagates along the string, and after being reflected at the support block, the two waves are superimposed on the string, forming a standing wave. By adjusting the string vibration frequency, string length and string tension, a stable standing wave can be obtained. Students can understand the standing wave phenomenon by observing the fluctuations of the string. Among them, the string vibration frequency is indirectly achieved by adjusting the motor speed through the motor speed adjustment device. The value of the string vibration frequency is measured by the photoelectric speed code disk to measure the motor speed and then converted by the single-chip microcomputer, which can be directly displayed by the digital tube; the string length is adjusted by sliding the support block left and right; the string tension is adjusted by adding or reducing the weight. Since the string is made of side-light visible optical fiber, the light source illuminates the string after power is turned on, making the string glow. Students can understand the standing wave phenomenon more intuitively by observing the glowing string, and there is no need to use an oscilloscope for observation, which is more intuitive and interesting. When demonstrating standing waves, by sliding the laser pen left and right so that the laser just illuminates the node or antinode, students can distinguish between nodes and antinodes and further understand the characteristics of standing waves.

[0025] The experimental effect diagram of the standing wave phenomenon demonstrated by the standing wave demonstration instrument of the present invention is as follows: Figure 2 As shown, from Figure 2 It can be seen that through the demonstration of the standing wave demonstrator of the present invention, students can clearly observe the standing wave phenomenon and the antinodes and nodes.

[0026] The experimental diagram of the present invention using a laser pen to measure the length of a string is shown in FIG. Figure 3 As shown, from Figure 3It can be seen that the string position can be accurately located by irradiating with a laser pen in combination with a ruler.

[0027] When the standing wave demonstrator of the present invention is used for demonstration, the comparison diagram of the standing wave phenomenon under different parameters is as follows: Figure 4 As shown, from Figure 4 It can be seen that different standing wave phenomena can occur by adjusting different parameters.

[0028] The use of the standing wave demonstration instrument of the present invention can demonstrate the special interference phenomenon - standing wave in the process of wave interference teaching, so that students can understand the conditions for the generation of standing waves. At the same time, factors such as vibration frequency, string length, string tension and string material can be changed to provide students with quantitative exploration of the relationship between standing waves and physical quantities such as vibration frequency, string length, string tension and string density. When exploring the relationship between vibration frequency and wavelength, the string tension can be kept unchanged, the vibration frequency can be changed, the string length can be adjusted, and the relationship between the two in the standing wave can be discussed; when exploring the relationship between wavelength and tension, the vibration frequency can be kept unchanged, and the string tension can be changed by changing the number of weights hanging on the string to observe the string vibration phenomenon; using the same method, keeping the string length unchanged, the relationship between vibration frequency and tension can be explored, and different types of strings can be replaced, the string density can be changed, and the influence of string density on wave velocity can be explored. The inventor evaluated the experimental instrument through a large number of experiments, and the experimental results are consistent with the law presented by the string vibration eigenvalue equation. Its experimental principle is correct, the operation is simple and flexible, and the experimental phenomenon is stable and obvious, which can play an important role in teaching demonstration and experimental exploration. At the same time, through the observation of interesting physical phenomena, students' spirit of scientific inquiry can also be stimulated.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A standing wave demonstrator, characterized in that: The invention comprises a base, one end of which is provided with an electrically connected motor and a motor speed regulating device, and the other end is provided with a fixed pulley; a speed measuring code disk with an eccentric shaft is provided on the rotating shaft of the motor, a vibration rod is provided on the eccentric shaft parallel to the speed measuring code disk, one end of the vibration rod is provided with a first slide groove along the length direction of the vibration rod, the eccentric shaft passes through the first slide groove and can slide in the first slide groove; a support frame is provided on the end of the base between the motor and the fixed pulley close to the motor, the support frame is provided with a fixed shaft, the middle part of the vibration rod is sleeved on the fixed shaft and can rotate around the fixed shaft; the other end of the vibration rod is fixed to one end of the string, the middle part of the string passes around the fixed pulley, and the other end is connected with a weight to make the string in a straight state; a support block is provided on the base directly below the string, the string can just be pressed on the top of the support block, and the string between the support block and the vibration rod is parallel to the base; the height of the fixed pulley is lower than the height of the support block.

2. The standing wave demonstrator according to claim 1, characterized in that: A hanging ring is fixed on one end of the string close to the weight, and the weight is hung on the hanging ring.

3. The standing wave demonstrator according to claim 1, characterized in that: The string is a side-light visible optical fiber, and a light source is fixed to one end of the string close to the weight. When the light source is powered on, the light emitted is directed directly to the string, making the string glow.

4. The standing wave demonstrator according to claim 1, characterized in that: A second slide groove is arranged on the upper surface of the base, directly below the string line and parallel to the string line. The bottom of the support block extends into the second slide groove and can slide along the second slide groove.

5. The standing wave demonstrator according to claim 1, characterized in that: A scale is arranged on the base parallel to the string line to facilitate measuring the length of the string line.

6. The standing wave demonstrator according to claim 1, characterized in that: A straight laser pen which can slide parallel to the string is fixed above the string, and the laser emitted by the straight laser pen is directly facing the string.

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