Arduino-based comprehensive magnetic field tester

Abstract

The invention discloses a comprehensive tester of multiple magnetic fields based on Arduino. The Arduino single-chip microcomputer, a Hall sensor and other devices are adopted to develop a comprehensive experimental instrument capable of measuring multiple magnetic fields. Based on the understanding of different magnetic field measurement methods and the integration of relevant experimental equipment, the measurement experiments of a constant magnetic field, an alternating magnetic field and a geomagnetic field are combined to reflect the difference among the constant magnetic field, the alternating magnetic field and the geomagnetic field in electromagnetic effects, measure the size and direction of the magnetic field, and help students recognize and understand the distribution of the magnetic fields of a current-carrying circular coil and a Helmholtz coil, as well as the size of the component of the geomagnetic field parallel to the ground.

Description

Technical Field

[0001] The present invention relates to the field of physical testing technology, and more particularly to an Arduino-based comprehensive tester for multiple magnetic fields. Background Art

[0002] At present, the progress of modern science and technology has led to the continuous innovation of new processes, new technologies and new materials. In the new environment, physical experiments can help students understand that the development of modern science is inseparable from the support of basic physics. Physical experiments reflect the theoretical reasons for the gradual progress of modern science and technology from a small perspective. Many scientific and technological products, improved new products, etc. that have appeared now have concentratedly demonstrated the changing power of modern science and technology. However, some experiments that reflect modern science and technology are not just as simple as using balances, spring scales, thermometers, student power supplies, voltages, ammeters, sensitive ammeters, etc. to explain and verify. Modern industry or technological development has made great progress and changes in accuracy and performance. Traditional physical experimental instruments are difficult to express and express the key contents of these science and technologies. Therefore, it is urgent to use new experimental instruments to replace old and aging physical experimental instruments.

[0003] Magnetic fields are widely used in many fields. In order to gain a deeper understanding of the characteristics of magnetic fields and to make better use of them, more and more attention has been paid to the measurement of magnetic fields. At present, many colleges and universities mainly use Hall effect to measure the magnetic field of solenoids and electromagnetic induction to measure alternating magnetic fields. In essence, they are all measurements of magnetic induction intensity, but in the experimental equipment, they are two completely separate sets of equipment, which adds unnecessary burden to the experimental space layout and experimental funds.

[0004] Therefore, how to achieve the integration of magnetic field measurement equipment is an urgent problem that technicians in this field need to solve. Summary of the invention

[0005] In view of this, the present invention provides a comprehensive tester of multiple magnetic fields based on Arduino. The Arduino single-chip microcomputer and the Hall sensor are adopted to develop a comprehensive experimental instrument capable of measuring multiple magnetic fields. Based on the understanding of different magnetic field measurement methods and the integration of relevant experimental equipment, the measurement experiments of the constant magnetic field, the alternating magnetic field and the geomagnetic field are combined to reflect the differences among the constant magnetic field, the alternating magnetic field and the geomagnetic field in the electromagnetic effects, and to measure the size and direction of the magnetic field, which is helpful to help students recognize and understand the distribution of the magnetic fields of the current-carrying circular coil and the Helmholtz coil, as well as the size of the component of the geomagnetic field parallel to the ground.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] An Arduino-based comprehensive tester for multiple magnetic fields, comprising a base plate, an Arduino single-chip microcomputer, an adjustable coil group, a universal ball, a detection coil, a compass, a lead screw slide rail, a magnetic induction intensity display screen, a current and voltage display screen, a single-coil and double-coil switch, a DC-AC conversion switch, a terminal and a coil spacing scale;

[0008] The Arduino single chip is electrically connected to the universal ball, the magnetic induction intensity display screen and the current and voltage display screen;

[0009] The universal ball is fixed on the screw guide rail and extends between the adjustable coil groups to achieve sliding in the x-axis direction, the y-axis direction and the z-axis direction;

[0010] The detection coil slides between the adjustable coil groups through the lead screw slide rail to achieve sliding in the x-axis direction and the y-axis direction;

[0011] The compass is movably fixed on the base plate;

[0012] The terminal is connected to the adjustable coil group through the AC-DC conversion switch;

[0013] The coil spacing scale is fixed on one side of the adjustable coil assembly;

[0014] The single-coil and double-coil switch connects the adjustable coil group, the current and voltage display screen, and the magnetic induction intensity display screen to realize single-coil or double-coil connection switching;

[0015] The AC-DC conversion switch is connected to the adjustable coil group, the current and voltage display screen and the magnetic induction intensity display screen.

[0016] Preferably, the AC-DC conversion switch is a group of switches, which can be turned simultaneously to achieve switching between AC and DC. When DC power is applied, the current and voltage display screen and the magnetic induction intensity display screen are turned on, and when AC power is applied, alternating magnetic field measurement is performed.

[0017] Preferably, the binding posts include DC binding posts and AC binding posts, which are connected to DC power and AC power respectively, so that the adjustable coil group generates a steady magnetic field and an alternating magnetic field respectively. The red DC binding post is connected to the positive pole, and the black one is connected to the negative pole, while the AC binding post can be either positive or negative.

[0018] Preferably, a Hall plate is provided in the universal ball, and the Hall plate is electrically connected to the Arduino single chip microcomputer.

[0019] Preferably, the universal ball comprises a fixed half ring, a rotating ring and a sphere; the sphere can be rotatably fixed at the center of the rotating ring, and the two ends of the rotating ring with the same rotation direction as the sphere can be rotatably fixed at the two ends of the fixed half ring.

[0020] Preferably, the universal ball is extended and fixed on the screw slide rail through a carbon rod, and the arc top end of the fixed half ring of the universal ball is fixedly connected to the carbon rod; the screw slide rail includes an x-axis slide rail, a y-axis slide rail and a z-axis slide rail, the z-axis slide rail is perpendicular to the y-axis slide rail and is slidably connected, and the x-axis slide rail is placed perpendicular to the plane of the y-axis slide rail and is slidably connected; one end of the carbon rod is slidably connected to the z-axis slide rail, and the other end of the carbon rod is fixedly connected to the universal ball.

[0021] It can be seen from the above technical solution that, compared with the prior art, the present invention discloses a multi-magnetic field comprehensive tester based on Arduino, which integrates devices such as Helmholtz coils, Arduino single-chip microcomputers, Hall sensors, compasses and induction coils to obtain a magnetic field comprehensive experimental instrument that can measure the magnitude and direction of magnetic fields such as the geomagnetic field, steady magnetic field, alternating magnetic field, etc., and can quantitatively study the magnetic field. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0023] Figure 1 The accompanying drawing is a schematic structural diagram of a multi-magnetic field comprehensive tester based on Arduino provided by the present invention;

[0024] Figure 2 The accompanying drawing is a schematic structural diagram of the tester provided by the present invention from another angle;

[0025] Figure 3 The accompanying drawing is a top view of the instrument provided by the present invention;

[0026] Figure 4 The accompanying drawing is a schematic diagram of the structure of a universal ball provided by the present invention;

[0027] Figure 5 The accompanying drawing is a circuit diagram of a coil provided by the present invention;

[0028] Figure 6 The accompanying drawing is a schematic diagram of the relationship between the magnitude and position of the induced current on the x-axis of the Helmholtz coil provided by the present invention;

[0029] Figure 7The accompanying drawing is a schematic diagram of the relationship between the magnitude and position of the induced current on the x-axis of the Helmholtz coil provided by the present invention;

[0030] Figure 8 The accompanying drawing is a schematic diagram of the relationship between the measurement of induced electromotive force and the angle of the magnetic field coil provided by the present invention;

[0031] Fig. 9 The accompanying drawing is a schematic diagram of a steady magnetic field in the X-axis direction of a measuring circular coil provided by the present invention;

[0032] Fig.10 The accompanying drawing is a schematic diagram of a Y-axis steady magnetic field of a measuring circular coil provided by the present invention;

[0033] Fig.11 The accompanying drawing is a schematic diagram of a steady magnetic field in the X-axis direction of a Helmholtz coil provided by the present invention;

[0034] Fig.12 The accompanying drawing is a schematic diagram of the steady magnetic field distribution in the Y-axis direction of the Helmholtz coil provided by the present invention;

[0035] Fig.13 The accompanying drawing is a schematic diagram of the X-axis steady magnetic field distribution of the double coils provided by the present invention;

[0036] Fig.14 The accompanying drawing is a schematic diagram of the steady magnetic field distribution in the Y-axis direction of the double coil provided by the present invention;

[0037] Fig.15 The accompanying drawing is a schematic diagram for comparing the theoretical value and experimental value of the geomagnetic field provided by the present invention;

[0038] Fig.16 The accompanying drawing is a schematic diagram of a Helmholtz coil provided by the present invention;

[0039] Fig.17 The accompanying drawing is a schematic diagram of the magnetic field at a certain point outside the axis of a single circular coil provided by the present invention;

[0040] Fig.18 The accompanying drawing is a schematic diagram of the magnetic field of the Helmholtz coil provided by the present invention.

[0041] In the attached drawings: 1-base plate, 2-adjustable coil group, 3-universal ball, 31-fixed half ring, 32-rotating ring, 33-sphere, 34-carbon rod, 4-detection coil, 5-compass, 6-screw slide, 7-magnetic field strength display screen, 8-current and voltage display screen, 9-DC-AC conversion switch 10-single and double coil switch, 11-binding post, 12-coil spacing scale. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The embodiment of the present invention discloses a multi-magnetic field comprehensive tester based on Arduino, comprising a base plate 1, and an Arduino single chip microcomputer, an adjustable coil group 2, a universal ball 3, a detection coil 4, a compass 5, a screw guide rail 6, a magnetic induction intensity display screen 7, a current and voltage display screen 8, a DC-AC conversion switch 9, a single and double coil switch 10, a terminal 11 and a coil spacing scale 12 arranged on the base plate 1;

[0044] The Arduino single chip is electrically connected to the universal ball 3, the magnetic induction intensity display screen 7 and the current and voltage display screen 8;

[0045] The universal ball 3 is fixed on the screw guide rail 6 and extends between the adjustable coil group 2 to achieve sliding in the x-axis direction, the y-axis direction and the z-axis direction;

[0046] The detection coil 4 slides between the adjustable coil group 2 through the screw guide rail 6 to achieve sliding in the x-axis direction and the y-axis direction;

[0047] The compass 5 is movably fixed on the base plate 1;

[0048] The terminal 11 is connected to the adjustable coil group 2 via the AC-DC conversion switch 9;

[0049] The coil spacing scale 12 is fixed on one side of the adjustable coil assembly 2;

[0050] The single-coil and double-coil switch 10 is connected to the adjustable coil group 2, the current and voltage display screen 8 and the magnetic induction intensity display screen 7 to realize the switching between single coil and double coil;

[0051] The AC-DC conversion switch 9 is connected to the adjustable coil group 2, the current and voltage display screen 8 and the magnetic induction intensity display screen 7.

[0052] In order to further optimize the above technical solution, the AC-DC conversion switch is a group of switches, which can be turned on at the same time to achieve switching between AC and DC. When DC power is passed, the current and voltage display screen and the magnetic induction intensity display screen are turned on, and when AC power is passed, alternating magnetic field measurement is performed.

[0053] In order to further optimize the above technical solution, the terminal 11 includes a DC terminal and an AC terminal, which are connected to DC power and AC power respectively, so that the adjustable coil group generates a steady magnetic field and an alternating magnetic field respectively. The red DC terminal is connected to the positive pole, and the black one is connected to the negative pole, while the AC terminal can be either positive or negative.

[0054] In order to further optimize the above technical solution, a Hall plate is arranged in the universal ball 3, and the Hall plate is electrically connected to the Arduino microcontroller to achieve the measurement of the steady magnetic field.

[0055] In order to further optimize the above technical solution, the universal ball 3 includes a fixed half ring 31, a rotating ring 32 and a sphere 33; the sphere 33 can be rotatably fixed at the center of the rotating ring 32, and the two ends of the rotating ring 32 with the same rotation direction as the sphere 33 can be rotatably fixed at the two ends of the fixed half ring 31.

[0056] In order to further optimize the above technical solution, the universal ball 33 is extended and fixed on the screw slide 6 through the carbon rod 34, and the arc top of the fixed half ring 31 of the universal ball 33 is fixedly connected to the carbon rod 34; the screw slide 6 includes an x-axis slide, a y-axis slide and a z-axis slide, the z-axis slide is perpendicular to the y-axis slide and is slidably connected, and the x-axis slide is placed perpendicular to the y-axis slide plane and is slidably connected; one end of the carbon rod 34 is slidably connected to the z-axis slide, and the other end of the carbon rod 34 is fixedly connected to the universal ball.

[0057] In order to further optimize the above technical solution, a dedicated alternating magnetic field tester is used to provide the excitation current.

[0058] In order to further optimize the above technical solution, the Arduino microcontroller is provided with a USB interface, which can be connected to a power bank to power the Arduino microcontroller.

[0059] In order to further optimize the above technical solution, the adjustable coil group is connected to a single-double coil switch, which can control the connection of a single coil or a double coil of the adjustable coil group.

[0060] In order to further optimize the above technical solution, the present invention controls the Arduino single chip microcomputer through a program to convert the magnetic signal received by the Hall element into an electrical signal and output it. The connection circuit design of the adjustable coil group, DC-AC conversion switch, single-double coil switch and current and voltage display screen is as follows: Figure 5 As shown, the current and voltage display screen adopts a four-digit dual display. The single and double coil switch pins are respectively connected to the two coils of the adjustable coil group and the four-digit dual display. The DC-AC conversion switch is two sets of switches. One set of switch pins is respectively connected to a coil, a four-digit dual display and one of the binding posts in a set of binding posts, and the other set of switch pins is respectively connected to another coil and another binding post in a set of binding posts. A set of binding posts can be DC binding posts or AC binding posts.

[0061] Example

[0062] (1) When a DC power supply or an AC power supply is connected to the terminal on the left side of the instrument panel, the adjustable coil group generates a magnetic field, and the Hall sensor therein can output the magnitude of the magnetic field and display it on the left LCD screen; the magnitude of the magnetic field can be changed by changing the power supply voltage.

[0063] (2) Switching the single-coil and double-coil switch can switch the adjustable coil group to a single-coil or double-coil coil. If only one of the coils is energized, it will switch to a single coil; if both coils are energized and the distance between the two coils can be moved, it will switch to a double coil; if the distance between the two energized coils is equal to the coil radius, then the pair of coils is a Helmholtz coil, which is a special double coil structure.

[0064] (3) The wire frame and power supply are connected to the terminals on the right side of the panel. Changing the power supply voltage can change the current in the wire frame, and the current is displayed on the right side of the display.

[0065] Magnetic field of a current-carrying circular coil and a Helmholtz coil:

[0066] Magnetic field distribution on the axis of the Helmholtz coil Place a pair of circular coils with the same number of turns, the same winding method, and the same size on the same axis, and pass current in the same direction. When the distance between the two coils is equal to the radius of the ring, this combination is called a Helmholtz coil. Fig.16 shown.

[0067] According to Biot-Savart's law, the current element The magnetic induction intensity generated at any point in space for:

[0068]

[0069] In the formula, μ0 is the vacuum magnetic permeability, μ0 = 4π × 10-7 N / A 2 ; N is the number of coil turns, r is the vector radius from the current element to the space point, then for a single circular coil with a radius of R, the magnitude of the magnetic field generated on the central axis is:

[0070]

[0071] So

[0072]

[0073] when hour, The two inflection points of magnetic induction intensity are just right. Analyze the Helmholtz coil composed of two such circular coils, and assume that its magnetic field is B(x). When the exact expression of the remainder is not needed, the 2n-order Taylor formula with Peano remainder obtained by expanding B(x) by the power of (x-x0) is shown in formula (4), where x0=0 and n is a positive integer.

[0074]

[0075] In the Helmholtz coil, the distance between the two coils is R. According to the analysis results of the previous single coil, the center point O is exactly the inflection point of the magnetic field on the axis, so the coefficient of the third term in the expansion of B(x) is Due to the symmetry of the magnetic field, B(x) = B(-x), so the odd-order derivative coefficients in the above formula are …are all 0, and we can conclude

[0076]

[0077] From equation (5), we can see that the magnetic field B(x) formed on the axis of the Helmholtz coil is The range is relatively uniform.

[0078] The magnetic induction intensity on the axis of the Helmholtz coil is

[0079]

[0080] like Fig.17 As shown in the figure, it is a schematic diagram of the magnetic field of a single circular coil off-axis point. Considering that the magnetic field generated by the energized circular coil is symmetrical, the magnetic field distribution of the entire space generated by the Helmholtz coil can be known by studying any point P (x, y, 0) located in the xoy plane.

[0081] according to Fig.17 ,have but

[0082]

[0083] According to the vector cross multiplication operation rule, we get

[0084]

[0085] Then the magnetic induction intensity at point P generated by the energized circular coil is

[0086]

[0087] and

[0088]

[0089] So, B z=0.

[0090] make According to Taylor series expansion, we get

[0091]

[0092] The x- and y-direction components of the magnetic induction intensity can be approximated as:

[0093]

[0094]

[0095] Based on the analysis of a single energized circular coil, a Fig.18 The Helmholtz coil shown.

[0096] In the new coordinate system, the coordinates of the off-axis point relative to the two coils are According to the principle of magnetic induction intensity vector superposition, the magnetic field distribution of the Helmholtz coil off-axis point is obtained as follows:

[0097]

[0098] Among them, B 1x , B 2x , B 1y , B 2y They represent the axial and longitudinal components of the two circular coils at a point in space respectively; θ represents the angle between the directions of the magnetic field.

[0099] The principle of measuring magnetic field by electromagnetic induction method:

[0100] Assume that the uniform alternating magnetic field is (generated by a coil with alternating current)

[0101] B=B m sinωt (15)

[0102] The magnetic flux of a detection coil in a magnetic field is

[0103]

[0104] Where: N is the number of turns of the detection coil, S is the cross-sectional area of ​​the coil, and θ is Angle with the coil normal.

[0105] The induced electromotive force generated by the coil is

[0106]

[0107] Where ε m =NSωB m cosθ is the amplitude of the induced electromotive force when the coil normal and the magnetic field form an angle θ.m =NSωB m At this time, the amplitude of the induced electromotive force is the largest. If a digital millivoltmeter is used to measure the electromotive force of the coil at this time, the indication (effective value) of the millivoltmeter is U max Should be but

[0108]

[0109] B can be calculated m Come.

[0110] Principle of the geomagnetic field quantitative measurement experiment:

[0111] Place the precision compass in the middle of the center axis of the two coils. When the power is off, wait for the needle to deflect and stabilize (point to the direction of the geomagnetic field), and read the initial degree of the magnetic needle θ1. Turn on the student power, add a magnetic field B0 in the direction perpendicular to the geomagnetic field, wait for the needle to stabilize again, and read the degree of the magnetic needle deflection θ2. According to formula (19), the geomagnetic field B can be calculated.

[0112]

[0113] Method for measuring the magnetic field strength of a particle in all directions:

[0114] Most devices can only measure the magnetic field strength in the x-axis direction. So, by rotating the globe, we re-welded the Hall plate and used a 3D printer to create the following Figure 4 The miniature globe shown in the figure enables the Hall plate to rotate on the miniature globe, so that the magnetic field strength in all directions of a particle point of the Hall coil can be measured.

[0115] Example 1

[0116] The Arduino-based comprehensive magnetic field tester of the present invention can measure the magnetic field of a single coil, a Helmholtz coil, and a movable double coil, and realize the measurement of an alternating magnetic field and a geomagnetic field.

[0117] Coil measurement steps:

[0118] S11: Adjust the single and double coil switches to the single coil position, and only energize one of the coils; return the XYZ coordinates of the screw guide rail connected to the universal ball to zero, connect the power bank to the USB port on the instrument to power the Arduino microcontroller, and connect the DC terminal with the student power supply, turn on the student power supply and adjust it to a suitable current (the current should not be too large to avoid burning the double-digit meter); keep the ZY axes of the screw guide rail that controls the position of the universal ball constant at 0, and move the X axis to record a data every 1 cm for a total of twelve groups;

[0119] S12: Switch to the double coil position; adjust the coil spacing of the adjustable coil group to D = 10 cm; return the XYZ coordinates of the screw guide rail connected to the universal ball to zero, keep the ZY axes of the screw guide rail that controls the position of the universal ball constant at 0, move the X axis and record a data every 1 cm, a total of twelve groups;

[0120] S13: Switch to the double coil position; adjust the coil spacing to 12cm, 16cm or 20cm; return the XYZ coordinates of the screw guide rail connected to the universal ball to zero, keep the ZY axes of the screw guide rail that controls the position of the universal ball constant at 0, and move the X axis to record a data set every 1cm for a total of twelve groups.

[0121] Alternating magnetic field measurement steps:

[0122] S21: Remove the universal ball and use the detection coil for measurement. The detection coil uses an energized solenoid.

[0123] S22: Measure the distribution of magnetic field in different directions when the adjustable coil group forms a Helmholtz coil, so that the effective value of the excitation current is I = 0.800A, take the center of the circular current coil as the coordinate origin, measure a Umax value every 10°, and keep the excitation current value unchanged during the measurement process;

[0124] S23: Measure the distribution of the magnetic field on the axis of the Helmholtz coil, connect the adjustable coil group of various magnetic field comprehensive testers in series (note that the polarity cannot be reversed), change the terminal to the AC terminal, so that the effective value of the excitation current is still I=0.800A, take the center point on the axis of the two circular coils as the coordinate origin, measure a Umax value every 1cm, record the data and make a magnetic field distribution curve.

[0125] Geomagnetic field measurement steps:

[0126] S31: The compass of the multi-magnetic field comprehensive tester is placed in the center of the two coils; the compass uses a precision compass;

[0127] S32: Disconnect the power supply, wait for the pointer to deflect and stabilize (point to the direction of the geomagnetic field), rotate the multi-magnetic field comprehensive tester, and adjust the direction so that the magnetic field direction generated by the Helmholtz coil is orthogonal to the direction of the precision compass;

[0128] S33: Turn on the student power supply and superimpose the magnetic field of the Helmholtz coil. After the pointer stabilizes again, read the deflection angle of the magnetic needle. The size of the geomagnetic field parallel to the ground is calculated through the magnetic field generated by the Helmholtz coil and the deflection angle of the precision compass.

[0129] Example 2

[0130] Based on the experimental steps provided in Example 1, measurement data of the alternating magnetic field are obtained.

[0131] 1) Measure the X-axis alternating magnetic field of the Helmholtz coil

[0132] Pass an alternating current, measure the magnetic field distribution on the axis, and compare it with the theoretical value. In this experiment, the frequency of the alternating current is 50Hz, and the effective value of the current is 800mA; change the x position on the axis, and use formula B m =0.103U max ×10 -3 (T) is used to calculate the experimental value; formula (12) is used to calculate the theoretical value. The X-axis alternating magnetic field of the Helmholtz coil shown in Table 1 is the measured data of this experiment; Figure 6 It is a comparison curve between the theoretical value and the experimental value of this experiment. The blue curve is the theoretical value of the magnetic field, the red curve is the experimental value of the magnetic field, the horizontal axis represents the moving distance of the x-axis, and the vertical axis represents the magnitude of the magnetic field.

[0133] Table 1 Helmholtz coil X-axial alternating magnetic field

[0134]

[0135]

[0136] From the above data, we can know the distribution of magnetic field on the axis of the Helmholtz coil: the magnetic field inside the Helmholtz coil is basically uniform on the X axis, and the magnetic induction intensity outside the Helmholtz coil gradually decreases. And the magnetic field is distributed in a mirror-symmetrical manner about the center.

[0137] 2) Measure the Y-axis alternating magnetic field of the Helmholtz coil

[0138] Pass an alternating current, measure the magnetic field distribution on the Y axis, and compare it with the theoretical value. In this experiment, the frequency of the alternating current is 50Hz, and the effective value of the current is 800mA; change the Y position on the axis, Table 2 is the measured data of this experiment; Figure 7 It is a comparison curve between the theoretical value and the experimental value of this experiment. The blue curve is the theoretical value of the magnetic field, the red curve is the experimental value of the magnetic field, the horizontal axis represents the moving distance of the y-axis, and the vertical axis represents the magnitude of the magnetic field.

[0139] Table 2 Helmholtz coil X-axial alternating magnetic field

[0140]

[0141] From the above data, we can see that the experimental measurement values ​​are in good agreement with the theoretical values, and the magnetic field of the solenoid on the Y-axis hardly changes with the change of its distance on the Y-axis.

[0142] 3) Measure the relationship between the induced electromotive force and the angle between the magnetic field coils

[0143] From formula (17), we can see that the magnitude of the induced electromotive force is related to the magnitude of the magnetic induction intensity as well as the angle between the magnetic field and the coil normal. Next, we change the angle between the magnetic field and the coil normal to analyze the magnitude of the induced electromotive force. Figure 8 They are the corresponding data and measurement graphs respectively. The blue curve is the theoretical value of the magnetic field, the red curve is the experimental value of the magnetic field, the horizontal axis represents the angle between the coil and the magnetic field direction, and the vertical axis represents the magnitude of the magnetic field.

[0144] Table 3 Relationship between measured induced electromotive force and magnetic field coil angle

[0145]

[0146] As can be seen from the figure, the induced electromotive force is maximum when the angle is zero or 180 degrees, and minimum when the angle is 90 degrees.

[0147] Example 3

[0148] Based on the experimental steps provided in Example 1, the measurement data of the steady magnetic field is obtained.

[0149] 1) Measure the X-axis steady magnetic field of the circular coil

[0150] A steady DC current is passed through the electrode, and the magnetic field distribution on the X axis is measured and compared with the theoretical value. In this experiment, the current value is 250mA; the x position is changed on the axis, and Table 4 is the measured data of this experiment; Fig. 9 It is a comparison curve between the theoretical value and the experimental value of this experiment. The blue curve is the theoretical value of the magnetic field, the red curve is the experimental value of the magnetic field, the horizontal axis represents the moving distance of the x-axis, and the vertical axis represents the magnitude of the magnetic field.

[0151] Table 4 Measurement of the X-axis steady magnetic field of the circular coil

[0152]

[0153] Depend on Fig. 9 From Table 4, we can see that the distribution of the magnetic field on the axis of the current-carrying circular coil is roughly consistent with the theoretical value. The magnetic field intensity is the largest at the center of the axis and gradually weakens toward both sides. The value of the magnetic induction intensity is the largest at the center of the circle on the axis of a single circle, and the magnetic induction intensity on the axis slowly decreases as the distance from the center increases. The magnetic field on both sides of the center is symmetrically distributed, and the experimental and theoretical values ​​of the magnetic induction intensity at each point are very close, indicating that the experimental and theoretical values ​​are highly consistent.

[0154] 2) Measure the Y-axis steady magnetic field of the circular coil

[0155] A steady DC current is passed through the magnet to measure the magnetic field distribution on the Y axis and compare it with the theoretical value. In this experiment, the current value is 250mA; the x position is changed on the axis. Table 5 is the measured data of this experiment; Fig.10 It is a comparison curve between the theoretical value and the experimental value of this experiment. The blue curve is the theoretical value of the magnetic field, the red curve is the experimental value of the magnetic field, the horizontal axis represents the moving distance of the y-axis, and the vertical axis represents the magnitude of the magnetic field.

[0156] Table 5 Measurement of the steady magnetic field in the Y-axis direction of the circular coil

[0157] Steady current / mA x-axis / cm z axis / cm y axis / cm Magnetic field experimental value / Gs Theoretical magnetic field value / Gs error 250.00 0.00 0.00 -2.50 6.22 6.17 0.81％ 250.00 0.00 0.00 -2.00 6.16 6.09 1.15％ 250.00 0.00 0.00 -1.50 6.09 6.02 1.16％ 250.00 0.00 0.00 -1.00 6.02 5.97 0.84％ 250.00 0.00 0.00 -0.50 5.97 5.94 0.51％ 250.00 0.00 0.00 0.00 5.95 5.93 0.34％ 250.00 0.00 0.00 0.50 5.97 5.94 0.51％ 250.00 0.00 0.00 1.00 6.00 5.97 0.50％ 250.00 0.00 0.00 1.50 6.07 6.02 0.83％ 250.00 0.00 0.00 2.00 6.15 6.09 0.99％ 250.00 0.00 0.00 2.50 6.20 6.17 0.49％

[0158] The distribution of the magnetic field on the horizontal axis of the current-carrying circular coil is roughly consistent with the theoretical value. The magnetic field intensity is the smallest at the center of the horizontal axis and gradually increases towards both sides. The value of the magnetic induction intensity is the smallest at the center of the single circle on the horizontal axis, and the magnetic induction intensity on the horizontal axis increases slowly as the distance from the center of the circle increases. The magnetic field on both sides of the center of the circle is distributed symmetrically, and the experimental and theoretical values ​​of the magnetic induction intensity at each point are very close, indicating that the experimental and theoretical values ​​are highly consistent.

[0159] 3) Measure the X-axis steady magnetic field of the Helmholtz coil

[0160] A steady DC current is passed through the Helmholtz coil, and the magnetic field distribution on the X axis is measured and compared with the theoretical value. In this experiment, the current value is 250mA; the x position is changed on the axis, and Table 6 is the measured data of this experiment; Fig.11 It is a comparison curve between the theoretical value and the experimental value of this experiment. The blue curve is the theoretical value of the magnetic field, the red curve is the experimental value of the magnetic field, the horizontal axis represents the moving distance of the x-axis, and the vertical axis represents the magnitude of the magnetic field.

[0161] Table 6 Measurement of the steady magnetic field in the X-axis direction of the Helmholtz coil

[0162]

[0163] As can be seen from the figure, both experiments and theories show that within the larger range in the middle, the magnetic field size remains basically unchanged, indicating that the magnetic field is more evenly distributed in this area, and a uniform magnetic field within a certain range can be generated near the middle axis, and the experimental values ​​are consistent with the theoretical calculation results.

[0164] 4) Measure the steady magnetic field in the Y-axis direction of the Helmholtz coil

[0165] A steady DC current is passed through the Helmholtz coil, and the magnetic field distribution on the Y axis is measured and compared with the theoretical value. In this experiment, the current value is 250mA; the Y position is changed on the axis, and Table 7 is the measured data of this experiment; Fig.12 It is a comparison curve between the theoretical value and the experimental value of this experiment. The blue curve is the theoretical value of the magnetic field, the red curve is the experimental value of the magnetic field, the horizontal axis represents the moving distance of the y-axis, and the vertical axis represents the magnitude of the magnetic field.

[0166] Table 7 Steady magnetic field distribution of the Helmholtz coil in the Y-axis direction

[0167]

[0168]

[0169] It can be seen from the figure that the magnetic field in the center of the double coil in the y-axis direction is the largest and decreases at both ends.

[0170] 5) Measure the steady magnetic field in the X-axis direction of the double coil

[0171] A steady DC current is passed through the double coils, and the magnetic field distribution on the X axis is measured and compared with the theoretical value. In this experiment, the coil spacing is 12cm, and the current value is 250mA; the X position is changed on the axis, and Table 8 is the measured data of this experiment; Fig.13 It is a comparison curve between the theoretical value and the experimental value of this experiment. The blue curve is the theoretical value of the magnetic field, the red curve is the experimental value of the magnetic field, the horizontal axis represents the moving distance of the x-axis, and the vertical axis represents the magnitude of the magnetic field.

[0172] Table 8 The distribution of the steady magnetic field in the X-axis direction of the double coil

[0173]

[0174]

[0175] The magnetic field distribution on the horizontal axis of the double coil is roughly consistent with the theoretical value. The magnetic field intensity at the center of the axis is smaller than that at the center of a single coil, and gradually increases toward both sides, while the single coil decreases rapidly toward the outside. The magnetic field on both sides of the center of the circle is symmetrically distributed, and the experimental and theoretical values ​​of the magnetic induction intensity at each point are very close, indicating that the experimental and theoretical values ​​are highly consistent.

[0176] 6) Measure the steady magnetic field in the Y-axis direction of the double coil

[0177] A steady DC current is passed through the double coils, and the magnetic field distribution on the Y axis is measured and compared with the theoretical value. In this experiment, the coil spacing is 12cm, and the current value is 250mA; the X position is changed on the axis, and Table 9 is the measured data of this experiment; Fig.14 It is a comparison curve between the theoretical value and the experimental value of this experiment. The blue curve is the theoretical value of the magnetic field, the red curve is the experimental value of the magnetic field, the horizontal axis represents the moving distance of the y-axis, and the vertical axis represents the magnitude of the magnetic field.

[0178] Table 9 Distribution of the steady magnetic field in the Y-axis direction of the double coil

[0179]

[0180]

[0181] The magnetic field distribution of the double coil on the Y-axis is roughly consistent with the theoretical value. The magnetic field is the largest at the center of the double coil in the Y-axis direction and decreases at both ends.

[0182] 7) Measure the size of the magnetic field

[0183] A steady DC current is passed through the Helmholtz coil. The magnitude of the Earth's magnetic field can be measured using 2.3.1 and compared with the theoretical value. In this experiment, the coil spacing is 10.60 cm and the current value is 250 mA. The X position is changed on the axis. Table 10 is the measured data of this experiment. Fig.15 It is a comparison curve between the theoretical value and the experimental value of this experiment. The blue curve is the theoretical value of the magnetic field, the red curve is the experimental value of the magnetic field, the horizontal axis represents the deflection angle of the small magnetic needle, and the vertical axis represents the magnitude of the magnetic field.

[0184] Table 10 Data of measuring the geomagnetic field

[0185]

[0186] The measured and theoretical values ​​of the geomagnetic field are shown in the figure. Due to the error of the instrument and the influence of the surrounding environment, there is a slight error in the measured geomagnetic field. After conversion of each angle, the experimental and theoretical values ​​of the magnetic induction intensity are very close, indicating that the experimental and theoretical values ​​are highly consistent.

[0187] Beneficial effects of the present invention:

[0188] (1) Multifunctionality: The device is independent and reconfigurable and has a wide range of applications. By integrating the equipment and unifying the magnetic field environment, the device can be used to integrate alternating and constant magnetic field measurement equipment and can be used to set up constant magnetic field experiments.

[0189] (2) Diversity of magnetic field measurement methods: using electromagnetic induction to measure alternating magnetic fields; using the Hall effect to measure constant magnetic fields; using a small magnetic needle to measure the geomagnetic field;

[0190] (3) Introduction of advanced technologies and products: Arduino microcontrollers, Hall sensors and other hardware and software can be used to directly measure the magnitude of the magnetic field;

[0191] (4) Use the deflection angle of a small magnetic needle to measure the magnitude of the Earth's magnetic field. The deflection angle of a small magnetic needle does not require external power supply, the experimental device is simple, the measurement is accurate, and it can use the simplest method to obtain more difficult experimental data, which has great teaching value;

[0192] (5) The device can measure the magnetic field size inside and outside the Helmholtz coil in three dimensions and obtain real-time data, which is fast, convenient and accurate. The experiment contains many comprehensive knowledge points, which helps to cultivate students' divergent thinking and ability to solve complex problems, and has a wide range of applications.

[0193] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0194] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A comprehensive tester for multiple magnetic fields based on Arduino, characterized in that: It includes a base plate, and an Arduino single-chip microcomputer, an adjustable coil group, a universal ball, a detection coil, a compass, a lead screw slide rail, a magnetic induction intensity display screen, a current and voltage display screen, a single and double coil switch, a DC-AC conversion switch, a terminal and a coil spacing scale arranged on the base plate; The Arduino single chip is electrically connected to the universal ball, the magnetic induction intensity display screen and the current and voltage display screen; The universal ball is fixed on the screw guide rail and extends between the adjustable coil groups to achieve sliding in the x-axis direction, the y-axis direction and the z-axis direction; The detection coil slides between the adjustable coil groups through the lead screw slide rail to achieve sliding in the x-axis direction and the y-axis direction; The compass is movably fixed on the base plate; The terminal is connected to the adjustable coil group through the DC-AC conversion switch; The coil spacing scale is fixed on one side of the adjustable coil assembly; The single-double coil switch is connected to the adjustable coil group, the current and voltage display screen and the magnetic induction intensity display screen; The DC-AC conversion switch is connected to the adjustable coil group, the current and voltage display screen and the magnetic induction intensity display screen; The universal ball includes a fixed half ring, and the universal ball is extended and fixed on the screw slide rail through a carbon rod, and the arc top of the fixed half ring of the universal ball is fixedly connected to the carbon rod; the screw slide rail includes an x-axis slide rail, a y-axis slide rail and a z-axis slide rail, the z-axis slide rail is perpendicular to the y-axis slide rail and is slidably connected, and the x-axis slide rail is placed perpendicular to the plane of the y-axis slide rail and is slidably connected; one end of the carbon rod is slidably connected to the z-axis slide rail, and the other end of the carbon rod is fixedly connected to the universal ball.

2. The Arduino-based comprehensive magnetic field tester according to claim 1, characterized in that: The binding posts include DC binding posts and AC binding posts, which are connected to DC power and AC power respectively.

3. The Arduino-based comprehensive magnetic field tester according to claim 1, characterized in that: A Hall plate is arranged in the universal ball, and the Hall plate is electrically connected to the Arduino single chip microcomputer.

4. The Arduino-based comprehensive magnetic field tester according to claim 1, characterized in that: The universal ball also includes a rotating ring and a sphere; the sphere can be rotatably fixed at the center of the rotating ring, and the two ends of the rotating ring with the same rotation direction as the sphere can be rotatably fixed at the two ends of the fixed half ring.

Images