72 results about "Lenz's law" patented technology

The invention discloses an overrunning clutch which comprises a base, a bearing, a transmission shaft, a limiting ring, fixed shafts, rotary shafts, magnetic-steel fixed blocks and non-magnetic-conducting metal discs. The non-magnetic-conducting metal discs are fixed at the upper end of the transmission shaft, the limiting ring is fixed at the outer edge of the upper end of the base, each fixed shaft is fixed at the upper end of the base along the inner side of the limiting ring, each rotary shaft is fixed on one fixed shaft in a pivoted manner, a pair of the magnetic-steel fixed blocks are fixed on each rotary shaft, a pair of permanent magnets opposite in polarity are fixed at second ends of each pair of the magnetic-steel fixed blocks, and the non-magnetic-conducting metal discs are disposed among the rotary shafts. By utilizing the Lenz's law, force is transmitted onto the base from the transmission shaft, and contactless overrun clutching is realized. The permanent magnets do not contact with the non-magnetic-conducting metal discs, so that friction is not caused, impact force is extremely small, abrasion cannot be caused, and the service life of the clutch is greatly prolonged.

Conductive lap windings are interleaved with conventional loops in the stator of a motor-generator. The rotor provides magnetic induction lines that, when rotated, cut across the lap windings and the loops. When the rotor is laterally displaced from its equilibrium axis of rotation, its magnetic lines of induction induce a current in the interleaved lap windings. The induced current interacts with the magnetic lines of induction of the rotor in accordance with Lenz's law to generate a radial force that returns the rotor to its equilibrium axis of rotation.

The invention discloses an electromagnetic induction comprehensive experiment device capable of obtaining and recording all information of an electromagnetic induction process to be analysed and studied. A cylindrical permanent magnet (1) used by the device passes through a guide tube (3) upright fixed on a special bracket (4) and free falls to a magnet adsorption pad (5) by gravitation; two multi-tap induction coils (2) provided outside the guide tube and capable of moving up and down transmits all changing processes of an induced electromotive force, which is generated when the cylindrical permanent magnet (1) passes, to two passages of a digital storage oscillograph (6) to be displayed and stored. The invention also discloses a manufacturing method of the special bracket and the multi-tap induction coils. The device has a simple structure, is convenient to operate, realizes measurement of physical quantities such as gravity, magnetic force and the like while quantification-studying Faraday's law of electromagnetic and Lenz's law.

The invention describes a multiple lamp balance transformer and a drive circuit. The multiple lamp balance transformer has two magnetic cores with a closed magnetic flux path and two coils wound around the closed magnetic flux path. The two coils have the same number of windings. The impedance property of the coil and Lenz's Law are used to balance the operating current of the lamps connected to the coils. The drive circuit has a multiple lamp balance transformer connected to several lamps, and a boost transformer uses a controller to supply the current and voltage to the lamps. A current detect / protect circuit connected to the coils and the controller detects the current passing through the coils and converts the operating current of the lamp into a voltage to be sent to the controller, so that the controller controls and provides sufficient power to the lamps.

The invention relates to a motion control method for permanent magnet spherical motor quaternion feedback linearization. A stator coil of an applicable motor is located at the vertexes, the ridge midpoints and the centroids of an inscribed regular octahedron of a stator spherical shell; and N and S poles of permanent magnet poles are alternately distributed at the vertexes of an inscribed regular hexahedron of a rotor spherical shell. The motion control method includes the steps of establishing a rotor electromagnetic torque model according to a PMSM stator and rotor structure and a Lorentz rule; establishing a stator counter electromotive force model according to the PMSM stator and rotor structure and a Lenz's law; establishing a rotor kinematic model according to quaternion characteristics; establishing a rotor kinetic model according to a rigid body Newton-Euler rotation formula; establishing a PMSM global motion model according to the kinematic model and kinetic model; performing coordinate transformation on the global motion model to obtain a decoupled global motion model; and performing feedback control on the decoupled global motion model to obtain a closed-loop control system.

The present invention belongs to the technical field of physics teaching demonstration experiment devices, and especially relates to an experiment device for demonstration of electromagnetism induction phenomenon in physics teaching. The device comprises a demonstration rack and an electromagnetic induction mechanism arranged on the demonstration rack; the electromagnetic induction mechanism comprises permanent magnets, demonstration channels arranged below the permanent magnets, induction coils winded at the outer surfaces of the demonstration channels and an indication bulb. One ends of thepermanent magnets are movably connected with the demonstration rack, two ends of the induction coils are provided with binding posts, and the indication bulb is connected with the binding posts through wires. Through comparison experiment, the electromagnetic induction demonstration experiment device for physics teaching allows students to clearly understand the Lenz's law, the right hand rule andthe relation of currents and forces so as to effectively improve the students' learning motility, train the students' initiative for problem thinking and problem solution and improve the learning efficiency.

The invention relates to a cage anti-falling speed reduction buffer device. The cage anti-falling speed reduction buffer device is composed of an electromagnetic induction speed reduction device and an auxiliary inflatable buffer device; an aluminum plate ring is fixed on a cage channel, when the cage falls, a speed sensor or an acceleration sensor exceeds a specified maximum value, automatic circuit conduction is achieved on the speed sensor or the acceleration sensor, the strong current generates a strong magnetic field, according to the Lenz's law, when the cage passes through the aluminumplate ring, the magnetic field of the induced current is always used for blocking the change of the magnetic flux of the induced current, the generated resistance enables the cage to achieve speed reduction to be descended, the cage is descended safely through the step type speed reduction, the safety of the personnel is guaranteed, and the first protection effect is achieved; and a proximity switch enables a trigger to act, the current is sent to an igniter, the sodium nitride propellant contained in the igniter is ignited, then a large amount of harmless gas which takes nitrogen as a main gas can be generated, an air bag is inflated to a full state, and a second protection effect is achieved. According to the cage anti-falling speed reduction buffer device, the design is simple, the weight of the cage cannot be increased, the long-standing technical problem that the cage falls due to the facts that the case suffers from rope breakage, failed braking and failure of an anti-falling device are solved, the work is reliable, the safety performance is high, and the practicability is high.

The invention provides a visual demonstration instrument for the Lenz's law, and the instrument comprises a spiral tube, a coil, a visual line, a first binding post, a controller, a second binding post, a sensitive ammeter, and a bar-shaped magnet. The beneficial effects of the invention lie in that a student can directly observe the changes of the size and direction of a current through the visual line when a magnetic pole moves in the spiral tube, so the student can easily understand the experiment phenomenon, can conclude an experiment law and can finally master the Lenz's law; the visual performance and interestingness of an experiment can be improved through employing an LED string to represent the current and the changes of the size and direction of the current; and the learning efficiency of the student can be greatly improved.

The invention discloses a metal powder selective laser melting defect suppression device and belongs to the technical field of metal additive manufacturing. According to the metal powder selective laser melting defect suppression device, according to the Lenz's law and the Hall effect principle, liquid-state conductive metal will produce electromagnetic force in the magnetic field in the flowing process, the force has great influences on the flowing behavior of a molten pool, and therefore the metallurgical defects of formed parts are inhibited. The metal powder selective laser melting defectsuppression device comprises an excitation device, a magnetic field measuring device and a magnetic field control device. The excitation device comprises a coil and an iron core which is placed insidethe coil; the magnetic field measuring device is composed of four magnetic field sensors which are distributed at the four corners of a work platform, and used for measuring the magnetic field strength of a forming area; and the magnetic field control device adjusts the current in the coil to control the magnetic field strength and direction. The device has the advantages of being simple in structure, convenient to adjust, low in cost, and being capable of easily assembled to an existing metal powder selective laser melting device and the like, and can effectively suppress the metallurgical defects of the formed parts.

An electronic dart game includes a dart and a dartboard provided with a frame and a main body for being shot by the dart. The dart game can be scored automatically for being provided a plurality of inductance coils on the frame and connected to a electronic scoring means. A point or a slender shaft of the dart is magnetized so that an electronic signal can be generated while the dart is shot to go through the inductance coils in accordance with the Lenz's law. Therefore, the chances for erroneous signal to occur are very slim. As the main body is designed directly to the frame, the dartboard has a stable one-piece surface, thus a player will have a similar satisfactory sensation as shooting onto a classical one-piece dartboard.

The invention relates to an electromagnetic buffering lift and a lift monitoring system and relates to the technical field of lift devices. The electromagnetic buffering lift comprises a lift shaft, a lift car and a buffering device, wherein the lift car and the buffering device are arranged in the lift shaft. The buffering device comprises deceleration coils and deceleration magnets. The deceleration coils are arranged at the bottom of the lift car. The deceleration magnets are arranged on the inner wall of the lift shaft. According to the electromagnetic buffering lift and the lift monitoring system, the structure is simple, non-contact type deceleration is achieved through the Lenz's law, the influence of collision on the lift car can be effectively avoided, and then people in the lift car can be prevented from being hurt; and in addition, the deceleration effect and the falling speed of the lift car are in direct proportion, so that the same lift device can be adapted to different falling heights, and the material problem of a buffer does not need to be considered.

The Superconducting Electrodynamic Turbine produces thrust by transferring momentum to the Earth, via the geomagnetic field. A pair of counter-rotating electrodynamic rotors, that are made from a Superconductor, act together to displace the surrounding geomagnetic field. The rotation of a Superconductor in the geomagnetic field, referred to as the exciting field, creates persistent eddy currents in the Superconductor. Lenz's Law states that an induced eddy current produces a magnetic field that opposes the relative change in the exciting field. A continuous increment of energy, or work, has to be expended to overcome the opposing force and to keep the counter-rotating electrodynamic rotors rotating at a constant rate. This work is transferred to the magnetic field. The Electrodynamic Turbine produces a unidirectional displacement in the exciting magnetic field, creating a force or thrust. The magnitude of the force can be modulated by changing the rotational speed of the electrodynamic rotors and the direction of the thrust can be reversed by reversing the direction of rotation. The Electrodynamic Turbine can also be used to convert momentum, in the presence of an exciting field, to rotational kinetic energy for power generation.

The invention discloses an electromagnetic damping shock absorber for a vehicle suspension, and belongs to the field of shock absorbers for vehicle suspensions. The electromagnetic damping shock absorber comprises an outer cylinder and a piston rod, wherein the outer cylinder comprises a stator iron core and a cake type three-phase winding; the cake type three-phase winding is fixedly connected to the internal of a piston cavity of the stator iron core according to a spiral layout method; the piston rod comprises a mover iron core and multiple sections of annular windings; the multiple sections of annular windings are fixedly connected in sequence at equal intervals to coat the mover iron core; and each annular winding is independently connected with a vehicle-mounted power supply system to form parallel connection. The electromagnetic damping shock absorber can autonomously form real-time motion damping according to the generation condition of relative motion in vehicle jolting; the generation process of the motion damping has no need to be assisted by a complex and expensive advanced feedback control system, a feedback system or an additional power element; and such parameters as the magnitude of damping force and the inherent frequency of damping are realized through adjusting the current magnitude or direction of the multiple sections of annular windings according to the classical Lenz's law of the physics.

The invention relates to a teaching instrument for demonstrating a superconducting characteristic. The teaching instrument comprises a superconducting ring, a magnetic rod, a magnetic block, a Dewar, a stainless steel ring, an aluminum ring, a copper ring and a magnetic block cushion, wherein the superconducting ring is manufactured by a high-temperature superconducting closed coil. The magnitude and direction of impedance of generated induced current and an induced current magnetic field to an original magnetic field when the magnetic flux of a closed loop consisting of three common metal materials and a superconducting wire is changed are compared to understand a Lenz's law, the zero-resistance characteristic of a superconducting material and peculiar characteristics of different metal materials. The teaching instrument also can be used for finishing the demonstration of a magnetic levitation experiment by using the high-temperature superconducting ring and the magnetic block.

The invention discloses a method for determining a cross section of an intelligent element of a fire circuit breaker. The method comprises the following steps of deducing a relation of the mass and a sectional area of the intelligent element according to a density formula; deducing a relation of specific heat and mass of a material used by the intelligent element, a rated current intensity of a circuit and a time parameter for disconnecting the circuit when the overcurrent occurs in the circuit according to the sectional area, heat absorption amount, temperature different and Joule-Lenz's law of a resistor and the intelligent element; calculating a sectional area expression of the intelligent element, establishing a sectional model of the intelligent element of the fire circuit breaker, and determining the sectional area of the intelligent element. According to the method, the condition that the sectional area of the intelligent element depends on the square of the rated current under the situation that the type of the material of the intelligent element is determined can be deduced, i.e. the sectional area of the intelligent element is determined by the square of the rated current, and the required sectional area is larger when the rated current is greater.

The invention discloses a modeling method for a multi-point grounding fault of a wound core under an inter-sheet short circuit, and the method comprises the steps that a relational expression among the length of a winding path, the width of a section and the number of winding stages of each stage of a silicon steel strip is built under the condition that the geometric parameters of an inner window of the wound core and the radius of an outer section of a core column are known; the sheet-to-sheet equivalent resistance of the wound core is deduced when no short circuit occurs; when inter-chip short circuit occurs, the short-circuit silicon steel sheets are equivalent to one silicon steel sheet, and equivalent resistance between the short-circuit silicon steel sheets and non-short-circuit sheets is derived; according to the obtained equivalent resistance, a wound core multi-point grounding fault circuit model is built, and short circuit and non-short circuit hierarchical total equivalent resistance is derived by using a circuit principle; the fault current of the section where the iron core grounding point is located can form a loop, the potential difference of the grounding point is obtained according to the change rate of the cross-linked magnetic flux in the iron core and the Lenz's law, and the calculated value of the fault grounding current is further obtained.

The invention discloses a Lenz's law control type buffering device. The device comprises a main supporting base plate. According to the device, the Lenz's law in physics is utilized, in other words, the direction of induced electromotive force is obtained from electromagnetic induction, the magnetic field of induced currents always blocks the change of the magnetic flux of the induced currents, and by utilizing the principle, magnets are put into copper pipes, so that when the magnets fall, the falling speed can be effectively reduced, and the buffering effect is further achieved; by utilizing the electromagnetic principle, field intensity generated by the currents is put into the copper pipes, the magnitude of the field intensity is changed by changing the magnitude of the currents, finally, according to the Lenz's law, the larger the field intensity is, the larger the resistance is when the magnets fall, the function of changing the buffering force is achieved, and internal air is exhausted outwards when the space is controlled to be compressed; and the speed is limited by the maximum flowing speed of the air, and in combination with the air buffering principle, the purpose of combined control of the buffering effect is achieved, and the buffering effect is obvious.

The invention belongs to the field of riveting machines, and particularly relates to a nut conveying and positioning method for nut riveting. The conveying and positioning method specifically comprises the following steps of feeding, conveying, positioning and riveting; a riveting machine is further involved in the conveying and positioning method and comprises a placement platform and a rivetinghead with the side wall being provided with a controller; the lower end of the riveting head is provided with a magnetic positioning block internally provided with a sensor, the upper side wall of themagnetic positioning block is fixedly connected with a connecting rod, and the upper end of the connecting rod extends into the riveting head; and the riveting head is internally provided with a sliding groove matched with the connecting rod, and a magnetic fixing block and a conveying tube which are arranged horizontally are arranged between a riveting head and the placement platform. By arranging an induction coil, in the process that a nut moves to a positioning opening under the attractive effects of the magnetic positioning block and the magnetic fixing block, the nut is powered on and has magnetism at the moment, thus the nut decelerates under the effect of the Lenz's law when getting close to the induction coil, and the nut can be prevented from hitting a positioning plate at a high speed.

The invention discloses a DCS control power grid power transmission line ice-preventing device. The DCS control power grid power transmission line ice-preventing device comprises an ice removing ring covering a power transmission line. The ice removing ring comprises an inner ring and an outer ring which are connected in a sleeved mode. An induction coil is arranged inside the outer ring, a curved surface rotating pattern is formed on the outer surface of the power transmission line, the surface, making contact with the power transmission line, of the inner ring is provided with a matched thread, and the matched thread is matched with the curved surface rotating pattern in a concave-and-convex mode. When the power transmission line transmits an alternating current, an alternating magnetic field around the power transmission line produces a current inside the induction coil, and a magnetic field generated by the current is interacted with the alternating magnetic field to produce the rotating push force to push the inner ring to drive the whole ice removing ring to rotate and move in the rotating direction of the surface of the power transmission line to remove the ice and snow. The Lenz's law electromagnetic induction principle is applied, the DCS control power grid power transmission line ice-preventing device rotates surrounding the power transmission line like the fact that a nut surrounds a bolt, and moves to scrape the residual snow ice and snow in the moving direction of the power transmission line, and the purpose of applying the device is achieved.

The invention discloses a multifunctional demonstrator for electromagnetics experiments. The demonstrator comprises a base, a fixing plate, a fixation frame, a rotation frame and a crank. The fixing plate is arranged above the base and rotatably connected with the base, the fixation frame and the rotation frame are fixedly arranged at the two ends of the fixing plate respectively, and the crank ishorizontally arranged on the rotation frame; a U-shaped rack is connected to the crank, opposite heteropolar strip-shaped magnets are arranged at the upper and lower ends of the U-shaped rack, and afirst through hole is formed in the portion, close to the upper portion of the side surface of the rotation frame, of the fixation frame; a first fixing column is arranged on the inner side surface ofthe fixation frame horizontally opposite to the first through hole, a second through hole is formed in the top of the fixation frame, and a second fixing column is arranged on the inner side surfaceof the bottom of the fixation frame vertically opposite to the second through hole. The multifunctional demonstrator for the electromagnetics experiments is simple in structural arrangement, high in visibility and visual and integrates multiple functions, and understanding of students to the Faraday's law of electromagnetic induction, the Lenz's law, the left hand rule and the right hand rule canbe deepened.

The invention relates to the technical field of financial electronic detection equipment, and provides magnetic field detection equipment for generating induced current by using the Lenz's law. The equipment comprises a shell, a coil is fixedly connected to the inner wall of the shell, an electromagnet is movably connected to the outer wall of the coil, an electric rotating shaft is movably connected to the inner wall of the shell, and a pin is movably connected to the outer wall of the electric rotating shaft. The outer wall of the pin is movably connected with a conversion rod. According tothe magnetic field detection equipment for generating the induction current by utilizing the Lenz's law, the magnetic field source continuously approaches, the magnetic field continuously approaches and passes through the coil, the coil generates the induction current according to the Lenz's law, the induction current increases along with the continuous approaching of the magnetic field, and the current direction in the wire is consistent with the induction current direction; therefore, the magnetic field generated by the electromagnet is opposite to the magnetic field of the close magnetic field source, the magnetic fields offset each other to hinder the magnetic field from influencing the display screen, and the Lenz's law is utilized to induce and offset the magnetic field to prevent incomplete screen display.

The invention discloses a safe and speed-controlled sightseeing descend channel based on Lenz's law and a control method thereof. The safe and speed-controlled sightseeing descend channel comprises avertical outer pipe channel, an electromagnet sightseeing cabin body and a lifting mechanism, wherein the vertical outer pipe channel is made of non-magnetized metal conductors, a sightseeing notch isformed in the side wall of the vertical outer pipe channel, and a buffer mechanism is arranged at the bottom of the vertical outer pipe channel; the electromagnet sightseeing cabin body is arranged in the vertical outer pipe channel, and the electromagnet sightseeing cabin body is connected with the lifting mechanism; and the electromagnet sightseeing cabin body comprises an electromagnet outer cabin and an insulating transparent inner cabin. According to the descend channel, an induction magnetic field generated by the movement of the electromagnet sightseeing cabin body in the vertical outer pipe channel is utilized to realize the controlled speed and slow descent of the electromagnet sightseeing cabin body in the vertical outer pipe channel, the descending process does not need to be controlled by a motor, the structure is simpler, operation is safe and reliable, the descent speed is convenient to control, the stimulation experience of sightseeing and rapid descent is achieved, andthe descend channel can be applied to sightseeing and entertainment facilities such as playgrounds, high-rise buildings.

The invention relates to teaching equipment for verifying the Lenz's law. The teaching equipment for verifying the Lenz's law comprises a base, a first insulating tube, a plurality of verifying coils,a plurality of light-emitting elements and a magnetic part, wherein the first insulating tube is arranged on the base, the plurality of the verifying coils are all wound around the first insulating tube and spaced apart one another, the plurality of the light-emitting elements are respectively connected to the plurality of the verifying coils, each of the light-emitting elements and the corresponding verifying coil form a closed loop, the magnetic part is used for being placed in the first insulating tube, and declines under the action of gravity, and the plurality of the verifying coils sequentially generate induced currents to drive the plurality of the light-emitting elements to emit light sequentially. The teaching equipment for verifying the Lenz's law is intuitive and easy to teach.

The invention belongs to the electromagnetism technical field and provides a series of novel techniques of a permanent magnet fusion rotary motor, a permanent magnet fusion linear motor, an electromagnetic fusion rotary motor, an electromagnetic fusion linear motor, a magnetic fusion train and a magnetic fusion welding machine. The basic nature of a motional magnetic field is utilized, and breakthroughs are made in the static magnetic field theory of Lenz's law. The magnetic fusion motor has the advantages of high magnetic field strength, high operation efficiency, fast response and high reliability. The magnetic fusion train can run on existing tracks, and therefore, huge costs of roadbed building are eliminated, and the magnetic fusion train has universality and great significance. According to the magnetic fusion welding machine, the structure of a traditional welding machine is simplified. According to the technical schemes and application of the invention, a magnetic yoke is connected with the same magnetic poles of a pair of magnetic fields, so that the magnetic fields can undergo magnetic fusion; solenoid windings which are provided with iron cores and are adjacent to the magnetic yoke are adopted as armatures; and with such new working principles adopted, the problems of difficulty in cooling and unreliable operation of a traditional motor can be solved.

The invention relates to the technical field of construction waste, and discloses a construction waste treatment device for automatically detecting screw looseness, the construction waste treatment device comprises a fixing screw and a shell, the top of the shell is fixedly connected with an indicator light, the inner wall of the shell is provided with a fixing groove, and the inner wall of the fixing screw and the outer side close to the fixing groove are fixedly connected with a closing coil. According to the construction waste treatment device for automatically detecting screw looseness, when a fixing screw is loosened due to external vibration, a sliding block can drive a connecting rod to move inwards under the action of a spring, the connecting rod drives a fixing block to move upwards, the relative area between a positive plate and a negative plate is changed to generate current, the current passes through a piezoresistor, and when the fixing screw is loosened, the electric contact is electrified, the electric contact electrifies the electromagnet through the conductive point, the electromagnet generates a magnetic field, the fixing screw is prevented from further loosening according to the Lenz's law and the principle of rejecting leaving, and therefore the problem that the fixing screw leaks out due to loosening is solved.

The invention discloses a Lenz's law demonstration instrument, and relates to the field of medical equipment. The Lenz's law demonstration instrument includes a housing, the housing is internally provided with a direct current power supply and a direct current boosting module which are connected, an output end of the direct current boosting module is connected with a cement resistor and an electrolytic capacitor in series; the Lenz's law demonstration instrument also includes a coil and a thyristor, the gate level of the thyristor is connected with a positive electrode of the power supply, the cathode of the thyristor is connected between the electrolyte capacitor and a negative electrode of the power supply, and the anode of the thyristor is connected with the coil in series and is then connected between the cement resistor and the electrolyte capacitor; a first switch is connected in series between a power supply positive electrode output end and the direct current boosting module; and a second switch is connected in series between the power supply positive electrode output end and the gate level of the thyristor. Supply voltage is boosted through a direct current boosting device to charge the electrolyte capacitor, and then the electrolyte capacitor is connected with the coil through control of the thyristor.

The invention relates to a multifunctional experimental device for Lenz's law, comprising a first bracket, a second bracket and a third bracket stacked in sequence from top to bottom. The first bracket and the second bracket are detachably connected, and the second bracket and the third bracket are fixedly connected. Multiple copper coils are arranged on the top surface of the top wall of the first bracket, and multiple grooves used to place magnets are arranged on the bottom surface of the top wall of the first bracket. Multiple circular holes for solenoids to pass through are arranged in thetop wall of the second bracket. Multiple step holes used to support the bottom ends of the solenoids are arranged in the top wall of the third bracket. The copper coils, the grooves, the circular holes and the step holes correspond in number and position. Each solenoid consists of an outer tube and an inner tube, and the outer tube sleeves the inner tube. Through the detachable connection betweenthe first bracket and the second bracket of the experimental device, the solenoids can be replaced conveniently, and the experimental device is more flexible and changeable in use.

The invention discloses a Lenz's law demonstration device, which comprises a non-magnetic-conductive and non-electric-conductive second column body and a non-magnetic-conductive metal ring which are used for conducting a contrast experiment, wherein at least one magnet is arranged above or below the second column body; a spacing distance is arranged between every two adjacent magnets; the metal ring can be sleeved outside the magnet and the second column body in a sliding manner; and orientations of the south and north poles of each magnet are consistent and are the same as the length direction of the column body. The Lenz's law demonstration device disclosed by the invention has the advantages of simplicity in structure, convenience in use, good demonstration effect, more intuition, and easiness in batch production, detachability and visualization.