CN110164265B - Vertical longitudinal wave standing wave experiment measurement device and method - Google Patents
Vertical longitudinal wave standing wave experiment measurement device and method Download PDFInfo
- Publication number
- CN110164265B CN110164265B CN201910400576.XA CN201910400576A CN110164265B CN 110164265 B CN110164265 B CN 110164265B CN 201910400576 A CN201910400576 A CN 201910400576A CN 110164265 B CN110164265 B CN 110164265B
- Authority
- CN
- China
- Prior art keywords
- metal spring
- current source
- fixed
- spring
- support
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Classifications
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09B—EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS
- G09B23/00—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes
- G09B23/06—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics
- G09B23/14—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics for acoustics
Abstract
The invention discloses a vertical longitudinal wave standing wave experimental measurement device and a method, wherein a first magnetic strip and a second magnetic strip are vertically fixed on a bracket, the north poles of the first magnetic strip and the second magnetic strip are positioned at the same end of the bracket, a metal spring is vertically arranged between the first magnetic strip and the second magnetic strip, one end of the metal spring is fixed on a cone of a loudspeaker, the other end of the metal spring is fixed on a force arm of a tension sensor, and a graduated scale is fixed on the bracket along the vertical direction. The influence of the mass of the spring on standing wave measurement can be effectively eliminated.
Description
Technical Field
The invention belongs to the technical field of photoelectric instruments, and particularly relates to a vertical longitudinal wave standing wave experimental measurement device and method.
Background
When two coherent waves with the same amplitude and frequency propagate oppositely on the same straight line, the superposed waves are called standing waves, and one-dimensional standing waves are a special case in wave interference. A number of stationary points, called nodes of the standing wave, appear on the chord line. The distance between two adjacent wave nodes is half wavelength. The observation of the standing wave formed on the string, and the study of the relationship between the wavelength of the standing wave and the tension, frequency and string density when the string vibrates are an important content in the current physical course, and an indispensable experimental process for facilitating students to understand teaching content in the experimental course. The experiment is widely applied to multiple disciplines, such as mechanics, acoustics, optics and the like. At present, most colleges and universities adopt transverse waves as a wave source of a standing wave experimental device, and the relationship between the resonant frequency and the standing wave wavelength, the tension and the chord line linear density when the string is forced to vibrate when the transverse waves propagate along the string is determined by an experimental method. Although widely used, this experimental method has a disadvantage that only a transverse wave phenomenon in a standing wave can be observed, and a vibration phenomenon of a longitudinal wave, which is an acoustic wave in many cases, cannot be exhibited. The observation of visual longitudinal wave standing waves is greatly helpful for students to understand the standing waves deeply, but the existing experimental method cannot achieve the effect well. The tension in the existing string standing wave demonstration device mostly adopts weights, one end of a string is connected with the weight with known weight in a demonstration experiment, and the other end of the string is fixed on an experiment table top outside a vibration device. The tension value is obtained by the weight, errors are easily caused by various factors, and the numerical value cannot be intuitively reflected. This is a step worth improving in the current general test methods. The standing wave experimental device is divided into two types of transverse waves and longitudinal waves, the number of standing waves of the transverse waves is large, the number of the longitudinal waves is small, the longitudinal waves are sound waves, and a visible standing wave result is not generated. How to observe visual longitudinal wave standing waves is helpful for students to understand the standing waves deeply, for example, one end of a spring is fixed on a tuning fork, the other end of the spring hangs down freely, and the standing wave phenomenon can be observed after the tuning fork vibrates, but the problems of unobvious nodes, uncertain node positions and the like exist generally. The existing spring longitudinal wave demonstration experiment device can only meet qualitative demonstration teaching due to low measurement precision, has the phenomena of node movement and the like caused by various factors, has poor demonstration effect and cannot carry out quantitative measurement.
Disclosure of Invention
The invention aims to solve the technical problem that standing wave wavelength measurement is inaccurate due to unstable nodes of the conventional standing wave experiment instrument, and provides a vertical longitudinal wave standing wave experiment measuring device and method, which can obtain stable vertical longitudinal wave standing waves and facilitate demonstration teaching and experimental measurement teaching.
The invention is realized by the following technical scheme:
a vertical longitudinal wave standing wave experiment measuring device comprises: the device comprises a bracket, a base, a tension sensor, a loudspeaker, an audio current source, a graduated scale, a metal spring, a guide rail, a power supply, a lead, a magnetic stripe I, a magnetic stripe II and a direct current source, wherein the bracket is vertically fixed on the side surface of the base, the tension sensor is fixed at the bottom of the bracket through the guide rail and can slide and be fixed on the guide rail along the vertical direction, the magnetic stripe I and the magnetic stripe II are vertically fixed on the bracket, the north poles of the magnetic stripe I and the magnetic stripe II are positioned at the same end of the bracket, the metal spring is vertically placed between the magnetic stripe I and the magnetic stripe II, one end of the metal spring is fixed on a paper cone of the loudspeaker, the other end of the metal spring is fixed on the force arm of the tension sensor, the loudspeaker is fixed at the top of the bracket, the graduated scale is fixed on the, the power supply is respectively connected with the audio current source, the tension sensor and the direct current source through wires, the audio current source is connected with the loudspeaker through the wires, and the direct current source is connected with the two ends of the metal spring through the wires.
Further, the bracket is made of rigid materials such as cast iron or steel. The support will have certain intensity, can support force sensor, magnetic stripe, metal spring and loudspeaker etc. of connection above to can stabilize the connection on the base, guarantee the firm of whole device.
Further, the base is made of metal materials such as cast iron. The base has certain intensity, can support audio current source, power, direct current power supply etc. of connecting above to can stabilize the setting on ground or other places, guarantee the firm of whole device.
Furthermore, the tension sensor is provided with a tension direct display module, and the tension can be directly read through a digital window.
Further, the cone of the horn is removed, leaving only the middle portion for securing the metal spring.
Furthermore, the audio current source can adjust the frequency of the audio current and has a frequency output numerical value display function.
Furthermore, the original length of the metal spring is between 60cm and 90cm, and the length of the metal spring after being fixed by the arm of force of the paper cone of the loudspeaker and the tension sensor is between 100cm and 150 cm.
Further, the north pole (N pole) and the north pole (N pole) of two magnets of magnetic stripe one, magnetic stripe two are placed along vertical direction relatively, and magnetic stripe one, magnetic stripe two are fixed on the support through steel sheet absorption respectively, and two rows of steel sheets are placed vertically, and the steel sheet plane is parallel to each other, and the steel sheet plane is perpendicular with the support plane.
Furthermore, the current of the direct current source is adjustable, and the vertical upward magnetic field force of the metal spring in the magnetic field formed by the two magnets is equal to the gravity of the metal spring by adjusting the current.
A vertical longitudinal wave standing wave experimental measurement method comprises the following steps:
(1) horizontally placing the metal spring on a table top, and measuring to obtain the original length L0 of the metal spring;
(2) one end of the metal spring is fixed on the cone of the loudspeaker to enable the metal spring to freely droop, and the length of the spring is larger than L0 due to the influence of the gravity of the spring;
(3) connecting two ends of the metal spring with the positive electrode and the negative electrode of the direct current source respectively through leads, and then adjusting the electrode direction and the current magnitude of the direct current source to ensure that the length of the metal spring is equal to L0;
(4) fixing the other end of the metal spring on a force arm of the tension sensor, and recording the length L of the metal spring at the moment;
(5) turning on a power switch of the audio current source, adjusting the current frequency of the audio current source, observing the formation condition of standing waves on the spring, and recording the corresponding frequency f and the reading T of the tension sensor when obvious standing waves are found;
(6) counting the number n of standing waves on the spring, and obtaining the wavelength lambda of the standing waves as L/n.
The invention has the following beneficial effects:
the invention realizes stable visual observation of the longitudinal wave standing wave, and can be used as the teaching of the longitudinal wave standing wave demonstration experiment; the device can also be used for researching the mutual relation among the wavelength, the frequency and the tension of the longitudinal wave after the standing wave is formed; the loudspeaker is driven to vibrate by the low-frequency signal source, so that the stable and accurate measurement of the standing wave frequency is ensured; the spring is vertically placed and in an initial state, the spring is pulled apart by a certain distance and is in a slightly stretched state, so that the formation and observation of the longitudinal wave standing wave are facilitated; the measures that the bottom of the spring is fixed and the vibration source is arranged right above the vertical direction are favorable for forming more stable standing waves; the spring is placed in a constant magnetic field, and the current passing through the spring is adjusted, so that the gravity of the spring is compensated by the magnetic field force, and the influence of the mass of the spring on standing wave measurement can be effectively eliminated; the tension is measured after a stable standing wave is formed, and the precision of the tension measurement value is high.
Drawings
Fig. 1 is a schematic structural diagram of a vertical longitudinal wave standing wave experimental measurement device of the present invention.
Detailed Description
To further describe the technical features and effects of the present invention, the present invention will be further described with reference to the accompanying drawings and detailed description.
A vertical longitudinal wave standing wave experiment measuring device comprises: the device comprises a support 1, a base 2, a tension sensor 3, a loudspeaker 4, an audio current source 5, a graduated scale 6, a metal spring 7, a guide rail 8, a power supply 9, a wire 10, a magnetic stripe I11, a magnetic stripe II 12 and a direct current source 13, wherein the support 1 is vertically fixed on the side face of the base 2, the tension sensor 3 is fixed at the bottom of the support 1 through the guide rail 8 and can slide and be fixed on the guide rail along the vertical direction, the magnetic stripe I11 and the magnetic stripe II 12 are oppositely arranged and fixed on the support 1 along the vertical direction, the metal spring 7 is vertically arranged in the middle, one end of the metal spring 7 is fixed on a paper basin of the loudspeaker 4, the other end of the metal spring 7 is fixed on a force arm of the tension sensor 3, the loudspeaker 4 is fixed at the top of the support, the graduated scale 6 is fixed on the support 1 along the vertical, The power supply 9 and the direct current source 13 are fixed on the base 2, the power supply 9 is respectively connected with the audio current source 5, the tension sensor 3 and the direct current source 13 through the conducting wires 10, the audio current source 5 is connected with the loudspeaker 4 through the conducting wires 10, and the direct current source 13 is connected with two ends of the metal spring 7 through the conducting wires 10.
Further, the bracket 1 is made of cast iron material and 2 meters high;
further, the base 2 is made of cast iron material, the interior of the base is hollow, and the panel is positioned at the top of the base;
furthermore, the tension sensor 3 adopts a JLBS-M2S miniature tension and pressure sensor of a force measuring sensor factory in Anhui province, the rated load is 0.01-5.00N, the tension sensor is provided with a tension direct display module, and the magnitude of the tension can be directly read out through a digital window;
further, the horn 4 is a 80-watt 4-ohm small and large horn loudspeaker with the diameter of 21cm of Shanghai Feile, a cone paper around the horn is taken away, and only the middle rubber part is reserved for fixing the metal spring 7;
further, the audio current source 5 adopts a YF-6 type PVM square wave signal generator and a YYMOS-1 type MOS tube of Shenzhen Yueque technology to amplify power, the frequency of the signal generator is adjustable within the range of 1 HZ-100 KHZ, the duty ratio is adjustable within the range of 0-100%, direct current is supplied for 3.3V-20V, and the MOS tube outputs 200W at most;
furthermore, the metal spring 7 is a customized metal spring with the wire diameter of 0.4mm, the outer diameter of 10mm and the length of 80cm in BondHUS in Zhejiang province, the original length of the metal spring 7 is 80cm, and the length of the metal spring 7 is 120cm after being fixed by the paper cone of the loudspeaker 4 and the force arm of the tension sensor 3;
furthermore, the north pole (N pole) and the north pole (N pole) of the two magnets of the first magnetic strip 11 and the second magnetic strip 12 are oppositely arranged along the vertical direction, the first magnetic strip 11 and the second magnetic strip 12 are respectively fixed on the bracket 1 through steel plate adsorption, the two rows of steel plates are vertically arranged, the planes of the steel plates are parallel to each other, and the plane of the steel plate is vertical to the plane of the bracket 1;
further, the power supply 9 adopts a general 500W high-power switching power supply;
further, the direct current source 13 is a Hangzhou blueprint electronic DCPS2422 type 400V/6A program-controlled communication voltage-stabilizing constant-current adjustable programmable high-precision current source, the current is adjustable, and the vertical upward magnetic field force of the metal spring 7 in a magnetic field formed by the two magnets is equal to the gravity of the metal spring 7 by adjusting the current.
Based on the device, the invention also provides a measuring method, which comprises the following steps:
(1) horizontally placing the metal spring 7 on a table, and measuring to obtain the original length L0 of the metal spring 7 which is 80 cm;
(2) one end of the metal spring 7 is fixed on the cone of the loudspeaker 4 to enable the metal spring to freely droop, and the length of the spring is larger than L0 due to the influence of the gravity of the spring;
(3) connecting two ends of the metal spring 7 with the positive electrode and the negative electrode of a direct current source 13 through leads respectively, and then adjusting the electrode direction and the current magnitude of the direct current source 13 to enable the length of the metal spring 7 to be equal to 80 cm;
(4) fixing the other end of the metal spring 7 on a force arm of the tension sensor 3, and recording the length L of the metal spring 7 at the moment as 120 cm;
(5) turning on a power switch of the audio current source 5, adjusting the current frequency of the audio current source 5, observing the formation condition of standing waves on the spring, and recording the corresponding frequency f to be 60Hz and the reading T to be 3.60N of the tension sensor when obvious standing waves appear;
(6) counting the number n of standing waves on the spring to be 12, and obtaining the wavelength lambda of the standing waves to be L/n to be 10 cm;
the above embodiments do not limit the present invention in any way, and all technical solutions obtained by taking equivalent substitutions or equivalent changes fall within the scope of the present invention.
Claims (5)
1. The utility model provides a vertical longitudinal wave standing wave experiment measuring device which characterized in that includes: the support, a pedestal, force sensor, loudspeaker, audio current source, the scale, metal spring, the guide rail, a power supply, the wire, magnetic stripe one, magnetic stripe two and direct current source, wherein, the support is vertical to be fixed on the base side, force sensor passes through the guide rail to be fixed in the support bottom and can slide and fix along vertical direction on the guide rail, magnetic stripe one, magnetic stripe two is vertical to be fixed on the support, magnetic stripe one is located the same end of support with the north pole of magnetic stripe two, vertically place metal spring between magnetic stripe one and the magnetic stripe two, metal spring's one end is fixed on loudspeaker's cone, metal spring's the other end is fixed on force arm, loudspeaker are fixed at the support top, the scale is fixed in on the support along vertical direction, audio current source, a power supply, direct current source are fixed on the base, the power supply respectively with audio current source, the tension sensor is connected with the direct current source, the audio current source is connected with the loudspeaker through a lead, and the direct current source is connected with two ends of the metal spring through leads; the current of the direct current source is adjustable, and the vertical upward magnetic field force of the metal spring in the magnetic field formed by the two magnets is equal to the gravity of the metal spring by adjusting the current.
2. The vertical longitudinal wave standing wave experimental measurement device of claim 1, wherein: the support is made of rigid materials, specifically cast iron or steel.
3. The vertical longitudinal wave standing wave experimental measurement device of claim 1, wherein: the base is made of metal material, specifically cast iron.
4. The vertical longitudinal wave standing wave experimental measurement device of claim 1, wherein: the first magnetic strip and the second magnetic strip are respectively fixed on the support through steel plate adsorption, the two rows of steel plates are vertically placed, the steel plate planes are parallel to each other, and the steel plate planes are perpendicular to the support plane.
5. A vertical longitudinal wave standing wave experimental measurement method is characterized by comprising the following steps:
(1) horizontally placing the metal spring on a table top, and measuring to obtain the original length L0 of the metal spring;
(2) one end of the metal spring is fixed on the cone of the loudspeaker to enable the metal spring to freely droop, and the length of the spring is larger than L0 due to the influence of the gravity of the spring;
(3) connecting two ends of the metal spring with the positive electrode and the negative electrode of the direct current source respectively through leads, and then adjusting the electrode direction and the current magnitude of the direct current source to ensure that the length of the metal spring is equal to L0;
(4) fixing the other end of the metal spring on a force arm of the tension sensor, and recording the length L of the metal spring at the moment;
(5) turning on a power switch of the audio current source, adjusting the current frequency of the audio current source, observing the formation condition of standing waves on the spring, and recording the corresponding frequency f and the reading T of the tension sensor when obvious standing waves are found;
(6) counting the number n of standing waves on the spring, and obtaining the wavelength lambda of the standing waves as L/n.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910400576.XA CN110164265B (en) | 2019-05-15 | 2019-05-15 | Vertical longitudinal wave standing wave experiment measurement device and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910400576.XA CN110164265B (en) | 2019-05-15 | 2019-05-15 | Vertical longitudinal wave standing wave experiment measurement device and method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110164265A CN110164265A (en) | 2019-08-23 |
| CN110164265B true CN110164265B (en) | 2021-04-27 |
Family
ID=67634575
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910400576.XA Expired - Fee Related CN110164265B (en) | 2019-05-15 | 2019-05-15 | Vertical longitudinal wave standing wave experiment measurement device and method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110164265B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110830886B (en) * | 2019-11-15 | 2021-04-13 | 钱孟泽 | Curve drawing system based on Arduino intelligent sound collection |
Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2226005C1 (en) * | 2002-12-16 | 2004-03-20 | Общество с ограниченной ответственностью фирма "СНАРК" | Training device for demonstration of wave optics |
| CN201449682U (en) * | 2009-08-08 | 2010-05-05 | 王宏宇 | Experimental instrument of magnetoelectric string standing wave |
| MX2009014164A (en) * | 2009-12-21 | 2011-06-21 | Univ Guanajuato | Device for generating transversal waves over a surface for observing undulating phenomena. |
| CN202196530U (en) * | 2011-09-05 | 2012-04-18 | 南阳理工学院 | Novel standing wave demonstration instrument |
| CN203325285U (en) * | 2013-07-23 | 2013-12-04 | 湖州文思必得科教仪器有限公司 | Rope wave demonstrating device |
| CN203535864U (en) * | 2013-10-23 | 2014-04-09 | 国家电网公司 | A circular standing wave generating device |
| US8849402B2 (en) * | 2011-03-21 | 2014-09-30 | General Electric Company | System and method for contactless power transfer in implantable devices |
| CA3011022A1 (en) * | 2015-02-27 | 2016-01-12 | Suncor Energy Inc. | System and method for recovering bitumen from a bitumen reserve using acoustic standing waves |
| CN106448358A (en) * | 2016-10-13 | 2017-02-22 | 兰州大学 | Experimental device for 2D standing wave characteristic research |
| CN207074522U (en) * | 2017-11-14 | 2018-03-06 | 华北电力大学（保定） | Two-dimentional standing wave resonance demonstrator |
| CN109637304A (en) * | 2019-01-23 | 2019-04-16 | 长江大学 | A kind of standing wave demonstrating instrument |
| CN109741666A (en) * | 2018-12-04 | 2019-05-10 | 南京林业大学 | Full-automatic standing wave resonance method sound velocimeter based on WIFI |
-
2019
- 2019-05-15 CN CN201910400576.XA patent/CN110164265B/en not_active Expired - Fee Related
Patent Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2226005C1 (en) * | 2002-12-16 | 2004-03-20 | Общество с ограниченной ответственностью фирма "СНАРК" | Training device for demonstration of wave optics |
| CN201449682U (en) * | 2009-08-08 | 2010-05-05 | 王宏宇 | Experimental instrument of magnetoelectric string standing wave |
| MX2009014164A (en) * | 2009-12-21 | 2011-06-21 | Univ Guanajuato | Device for generating transversal waves over a surface for observing undulating phenomena. |
| US8849402B2 (en) * | 2011-03-21 | 2014-09-30 | General Electric Company | System and method for contactless power transfer in implantable devices |
| CN202196530U (en) * | 2011-09-05 | 2012-04-18 | 南阳理工学院 | Novel standing wave demonstration instrument |
| CN203325285U (en) * | 2013-07-23 | 2013-12-04 | 湖州文思必得科教仪器有限公司 | Rope wave demonstrating device |
| CN203535864U (en) * | 2013-10-23 | 2014-04-09 | 国家电网公司 | A circular standing wave generating device |
| CA3011022A1 (en) * | 2015-02-27 | 2016-01-12 | Suncor Energy Inc. | System and method for recovering bitumen from a bitumen reserve using acoustic standing waves |
| CN106448358A (en) * | 2016-10-13 | 2017-02-22 | 兰州大学 | Experimental device for 2D standing wave characteristic research |
| CN207074522U (en) * | 2017-11-14 | 2018-03-06 | 华北电力大学（保定） | Two-dimentional standing wave resonance demonstrator |
| CN109741666A (en) * | 2018-12-04 | 2019-05-10 | 南京林业大学 | Full-automatic standing wave resonance method sound velocimeter based on WIFI |
| CN109637304A (en) * | 2019-01-23 | 2019-04-16 | 长江大学 | A kind of standing wave demonstrating instrument |
Non-Patent Citations (1)
| Title |
|---|
| 驻波演示仪的制作;周凤梅，杨植宗等;《物理与工程》;20010530(第11期);44-45 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110164265A (en) | 2019-08-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN2865179Y (en) | Harmonic frequency tester for loudhailer film | |
| CN110164265B (en) | Vertical longitudinal wave standing wave experiment measurement device and method | |
| CN203299081U (en) | Real-time liquid density measuring instrument | |
| RU103957U1 (en) | DEMONSTRATION SYSTEM FOR THE STUDY OF PHYSICAL PHENOMENA "UNIVERSAL" | |
| CN101650889A (en) | Simple pendulum | |
| CN212391927U (en) | Teaching device for demonstrating relation between sound and vibration | |
| Velasco et al. | A simple experiment for measuring bar longitudinal and flexural vibration frequencies | |
| CN211669285U (en) | Measuring electrode for electret surface potential tester | |
| Jacobs et al. | New experimental method of visualizing the electric field due to surface charges on circuit elements | |
| CN204462415U (en) | A kind of device utilizing hydrostatic pressure to measure acceleration of gravity | |
| CN210777431U (en) | Comprehensive demonstration experiment instrument for exploring ampere force characteristics | |
| CN202795841U (en) | Teaching model for demonstrating sound insulation effects of sound insulation boards with different thicknesses | |
| CN207198345U (en) | A kind of teaching metal detector | |
| CN207883280U (en) | Portable rule qin | |
| Rosenfeld et al. | A modified Zisman apparatus for measuring contact potential differences in air | |
| CN219738360U (en) | Sound characteristic demonstration instrument | |
| CN2334068Y (en) | Sound wave resonance instrument | |
| CN210777432U (en) | Demonstration experiment instrument for exploring interaction force between two parallel electrified leads | |
| CN210295458U (en) | Intelligent music education demonstrating board | |
| Hruška et al. | The first experiences with creating an experimental set for teaching physics | |
| CN210038012U (en) | Test device for researching stress factors affecting electrified lead | |
| CN214952128U (en) | Device for measuring stiffness coefficient of spring by using mobile phone magnetometer | |
| CN204480559U (en) | Natural frequency measures demonstration device | |
| CN212845755U (en) | Integrated circuit energy consumption testing arrangement for 5G | |
| CN212109833U (en) | Utensil is examined to annular isolator cavity |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20210427 |