The general research methods of natural science involved in middle school physics teaching mainly include observation, experiment, abstraction, idealization, comparison, analogy, hypothesis, model and mathematical methods. In physics classroom teaching, it is an important way to make full use of the history of physics to train students in general methods of natural science. Now give two examples to illustrate.
First, the typical experiments introduced in physics textbooks are used for method education.
Many famous experiments in the history of physics, such as Coulomb's torsional symmetry experiment, Rutherford-particle scattering experiment and chadwick's discovery of neutrons, can't be demonstrated in middle schools at present due to the limitation of equipment, but they are still written in textbooks. In doing so, the textbooks not only consider that they are important laws and theoretical foundations, which are helpful to develop thinking, but also consider the general methods that enable students to understand physical experiments from these specific examples. For example, each experiment includes putting forward experimental tasks, determining experimental methods and studying how to realize them, and logically processing the obtained experimental data to draw conclusions. Every stage of the experiment is closely intertwined with the theory and should be guided by the existing theory; Scientific instruments can help people overcome the limitations of sensory organs and make perceptual knowledge more objective, precise and accurate, so the design and use of scientific instruments play an important (sometimes even decisive) role in the success of experiments.
In classroom teaching, we should fully realize the educational function of these famous experiments, and spend some time and energy to introduce these experiments and their related historical background to students, so that students can feel the shock of the history of physics and the charm of physical experiment methods.
For example, in the teaching of Coulomb torsion balance experiment, the textbook simply shows the experimental device to the students and makes a simple introduction, which is unknown to many knowledge students behind this experiment. As early as thirty years before the Coulomb torsion balance experiment (1755), Franklin found that when the charged ball was suspended in the charged metal cavity, the charged ball was not stressed. In order to explain this phenomenon, he asked others to help him analyze and calculate. First, he obtained the hypothesis that the interaction between charges is inversely proportional to the square of the distance between charges. Is this assumption correct? Should it be written in the form of F∝ 1/r(2+δ)? In order to verify this relationship, Robinson measured the force between two charges by direct measurement in 1769. It is found that when the two charges are the same, the measured δ value is greater than zero, and when the two charges are different, the measured δ value is less than zero, and the δ value is about 0.06, so he speculates that the δ value should be zero. 1785, Coulomb made δ≤4× 10-2 by torsion balance experiment. Before this 1772, cavendish charged two concentric and connected metal balls by measuring the charge. After reaching a certain voltage, he disconnected the two balls, moved one ball to infinity to discharge, and verified inverse square law by measuring the charge of the other ball. What he did was δ≤2× 10-2. 1864, Maxwell improved Cavendish's method. By measuring the potential of charged ball, the measured value of δ was increased to the order of δ≤5× 10-5. After that, the measurement of δ value was based on Maxwell experiment and improved to improve the measurement accuracy. At present, the most accurate measurement was completed by three physicists in 1980, and the measured δ≤ 10- 19.
Why do you want to make such a measurement for more than 200 years? Why don't you stop when you arrive at the list of 10- 19? That's because all the laws of electromagnetism are based on inverse square law's premise, which also has a great relationship in modern physics, including whether the rest mass of photons is zero. Although the current measurement shows that the interaction between charges is very close to that of inverse square law and can be used in the usual physical research, from a scientific point of view, we still have a certain distance from inverse square law, and it may even be because of this distance that physical theory has had a great impact. When we introduce these physicists' step-by-step experimental designs and rich scientific research methods to students in classroom teaching, and explain to students why scientists try their best to accurately measure δ value, students will be shocked in their minds, which is incomparable to the effect produced by simple preaching and scripted teaching. Scientific moral education has also organically penetrated into the study of physics history.
Second, use the history of physics to reveal typical physical methods.
For example, phenomenological method and model method are one of the important methods in physics research, especially in the study of material structure. When learning the knowledge of atomic structure, we should fully study the discovery history of historical atomic structure, and let students experience the typical methods of physics through the study of history through teaching. The main physical historical materials are:
1897 After the discovery of electrons, J·J· Thomson of Britain thought that electrons should be part of atoms.
190 1 year, Piran of France mentioned in a speech that "the structure of atoms may have a planetary structure", which is an intuitive guess, so it has not attracted people's attention.
1903, Thomson put forward the "unified model", also known as the "raisin bread model". This hypothesis holds that the positive charge is a uniform sphere, and the electrons are uniformly distributed in the positive sphere.
1904 Japanese Kantaro Nagaoka thinks that electrons are an entity, and objects with positive charges are also entities and should be separated. Influenced by Maxwell's paper on the stability of Saturn's rings, he put forward a hypothesis similar to Saturn's structure.
1909, two of Rutherford's assistants, Geiger and marsden, conducted the scattering experiment of particle A under the guidance of Rutherford, and found an important phenomenon, that is, large-angle scattering, and the scattering angle of some particle A can exceed 90 degrees. The experimental results show that only one particle in 8000 A particles scatters at a large angle. This result cannot be explained by the previous phenomenological model. Geiger and marsden consulted their mentor Rutherford, and Rutherford immediately realized that the large-angle scattering of particle A could be caused by Coulomb electrostatic repulsion only if the positive charge was concentrated in a small range. Therefore, in 19 1 1, Rutherford put forward the "nuclear models of atoms", believing that positive charges are concentrated in the nucleus and electrons move around it.
19 13 years, Geiger and marsden proved that Rutherford's model was correct through experiments.
From this very brief review, it can be clearly seen that the model method is a very important method in studying the subject of material structure, which is often intuitive and imaginable. When applying model method, it is often phenomenological at first. According to a certain phenomenon or some phenomena, with the help of researchers' intuition and imagination, the author can sometimes draw inferences, describe the image and model that the author wants to give with the help of conclusions or images of some problems in other branches of other disciplines, and deal with related problems with mathematics, which can explain some phenomena and make predictions. Then this hypothesis will take the road of rationalism and be promoted to theory.
The history of physics plays a very important role in physics teaching, even in cultivating students' basic scientific research methods, its role is far more than the above two points.