Enlightenment From The Related Problems Involved In The High School Physics Dynamic Electromotive Force

Ordinary high school education has always been a hot topic for countless students.In the newly revised curriculum standard in 2017,the orientation of ordinary high school education was further clarified: the comprehensive quality of students was developed and the core literacy of students was cultivated.The goal of high school physics curriculum was integrated around this training goal,and the original "three-dimensional goal" was transferred to the physical concept,scientific thinking,experimental inquiry,scientific attitude and responsibility under the "core literacy";the ability and quality of the students were proposed.New requirements.As a means of educational evaluation,the examination is a measure of the level of education.It can test the completion of the course objectives and quantitatively analyze the students' learning effects.Based on the revision and condensing of the course standard,there are naturally higher standards for the test questions: appropriate difficulty and discrimination,reliable reliability and validity,novelty and unconventional,and the practical significance of advancing with the times.Therefore,the old questions of the past years can no longer meet our needs,and we need to compile more original questions,making our test questions more contemporary and diversified,and more conducive to further developing the overall quality of students.This is of great significance for the assessment of core literacy under the new curriculum standards.Among the many questions that are not good or bad,the college entrance examination question is undoubtedly the most authoritative material;in the college entrance examination question,the calculation question is the one that best reflects the comprehensive ability of the candidate.Through statistical analysis of the syllabus of the college entrance examination and the college entrance examination questions in the past two decades,the author finds that electromagnetic induction is a difficult point for students.In particular,the related problems related to the dynamic electromotive force are often comprehensive,and can be combined with mechanical knowledge such as uniform linear motion law and Newton's law of motion;and knowledge of energy related to kinetic energy theorem,energy conservation,etc.;Electromagnetic knowledgeof closed circuit Ohm's law,Joule's law,capacitance,electric quantity,induced electric field,etc.can be examined.At present,there is no special research on such topics,but such topics are almost mandatory for the college entrance examination every year,especially in Zhejiang and Shanghai.With the progress of the new curriculum reform,Zhejiang,Shanghai,etc.as early pilot areas,the direction of the topic can be used for reference,it can be inferred that the status of such topics in the college entrance examination will become more and more important.The author first counts the high-level examination questions in the past twenty years,and classifies and analyzes the topics related to electromagnetic induction in the calculation questions.It can be found that the general trend of computing propositions in recent years is to pay more attention to the foundation and emphasize the comprehensive ability.In the college entrance examination calculations,the electromagnetic induction class can be divided into two common situations: the first one is“induced electromotive force”,that is,the magnetic field in which the loop is located changes uniformly,and the area contained in the loop does not change;the second is“ The dynamic electromotive force,that is,the movement of the conductor relative to the magnetic field,causes the area contained in the loop to change,and the magnetic field of the loop does not change.Among them,the dynamic electromotive force is more comprehensive and involves more relevant test sites.Secondly,it refines the related problems involved in the dynamic electromotive force,analyzes the propositional ideas and laws of each test site,and obtains some valuable insights and enlightenments.First: If there is a magnetic field in the space,the induced current will cause the conductors in it to be subjected to amperage,which often involves mechanical problems.Ampere is a function of speed.If the external force is also a function of speed,so that the acceleration is a constant analysis of its motion state;or the external force is a constant force,then the external force is a variable force,the conductor The shifting motion will be performed,but when the Ampere force is equal to the external force,the conductor will stabilize and make a uniform linear motion,so that the critical speed can be obtained.Second: the process of electromagnetic induction often involves energy conversion problems.For example,if the external force overcomes the ampere work,the Joule heat generated in the loop can be obtained.When the ampere work is done,the electric energy is converted into other forms of energy.Third: the conductor rod to cut the magnetic induction line motion will generate the induced electromotive force.If there is a closed loop externally,there is an inducedcurrent;here,the resistance of the external circuit can be made a fuss,combined with the circuit analysis and Ohm's law.Fourth: The "twin model" involving both the induced electromotive force and the dynamic electromotive force should learn to use its production principle to analyze the change and constant of the total magnetic flux.Then,through examples,the propositional law of the related problems involved in the dynamic electromotive force is analyzed.Five examples are listed: the combination of dynamic electromotive force and mechanics knowledge,integration with energy knowledge,integration with circuit knowledge,integration with induced electromotive force,and comprehensive topics.A detailed analysis of the proposition points and propositional ideas for each type of topic.Finally,through a series of analysis and summary,the author creatively compiled two questions.They are: the dynamic electromotive force combined with the mechanics knowledge self-sufficiency test questions;the dynamic electromotive force combined with the electromagnetic knowledge self-sufficiency test questions.The relevant research results of electromagnetic induction have a profound impact on our lives.We should understand the application of basic disciplines in industrial and social development and serve the knowledge we have learned.Therefore,this study is very necessary.