UNIT 14. Text: “The Nature of the Electron and Wave Mechanics”.
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UNIT 14

 

I. Find out the words in the dictionary. Write them down and learn.

 

point electric charge, to behave like, collision, wave-particle duality, wavelength, value, probability, certainty, to measure     

 

II. Read the text. Use a dictionary, if necessary.

 

Text: “The Nature of the Electron and Wave Mechanics”.

 

According to the theory of wave mechanics, electrons orbiting a nucleus are not particles moving in orbits. There are standing waves that can be represented mathematically by what is called a wave function (which measures the probability of an electron being at a particular point in space). Peak values of this function can be taken to represent the orbits of the electrons. There is only a high probability – not a certainty – that the electrons will be found in the orbits. The certainty of the old theory has been replaced by a statistical probability measured by the wave function.

According to Heisenberg’s uncertainty principle, which arises from wave-particle duality, it is impossible to measure simultaneously both the position and momentum of a particle within certain limits. It can also be shown that it is similarly impossible to measure the total energy and lifetime of a particle simultaneously and with limitless accuracy.

Although the seemingly totally accurate and certain theories of classical physics have been replaced by the probability arguments and uncertainties of the quantum theory, it turns out that such concepts as Heisenberg’s uncertainty principle predict new, hitherto unexpected phenomena. For example, the law of conservation of energy has been interpreted in a new light; that is, energy cannot be created or destroyed but it may be developed from matter and turned into matter. The presence of this “created” energy – so-called vacuum particles – has been demonstrated experimentally.

 

III. Translate the following noun groups into Russian.

 

  1. point charges;                                  
  2. electron diffraction;
  3. wave-particle duality of electrons;       
  4. wave mechanics;
  5. a wave function;                                  
  6. values of the function;
  7. the certainty of the old theory;
  8. Heisenberg’s uncertainty principle;
  9. the position of a particle;
  10. the momentum of a particle;
  11. the law of conservation of energy;
  12. vacuum particles.

 

IV. Find English equivalents in the text.

 

1) точечный электрический заряд;

2) столкновение;

3) корпускулярно-волновой дуализм;

4) длина волны;

5) определенная точка в пространстве;

6) измерять одновременно;

7) в определенных пределах;

8) оказывается, что;

9) предсказывать;

10) следовательно.

 

 

V. Find Russian equivalents to the following expressions in the text.

 

1) according to the theory;

2) to behave like hard spheres;

3) it lies at the heart of the theory;

4) standing waves;

5) peak value of the function;

6) to interpret in a new light;

7) to develop from matter and turn into matter.

 

 

VI. Practice with someone asking and answering.

 

  1. In what way have electrons been considered previously?
  2. How do electrons behave?
  3. Where is the wave-particle duality of electrons recognized?
  4. What relationship assigns a wavelength to any particle of known mass and velocity?
  5. What is the nature of the electron according to the theory of wave mechanics?
  6. What principle makes it possible to measure simultaneously both the position and momentum of a particle within certain limits.

 

VII. Put disjunctive questions to the following sentences.

 

  1. Electrons sometimes behave like hard spheres.
  2. According to the theory of wave mechanics, electrons orbiting a nucleus are not particles moving in orbits, but standing waves.
  3. Heisenberg’s uncertainty principle arises from wave-particle duality.
  4. The law of conservation of energy has been interpreted in a new light.
  5. Energy cannot be created or destroyed.

 

VIII. Dictation-translation.

 

  1. Согласно теории волновой механики, электроны, вращающиеся вокруг ядра, не являются частицами, движущимися по орбитам.
  2. Волновая функция измеряет вероятность электрона, находящегося в определённой точке пространства.
  3. Определенность старой теории была заменена на статистическую вероятность, измеряемую с помощью волновой функции.
  4. Невозможно измерить одновременно и положение и импульс частицы в определенных пределах.
  5. Закон сохранения энергии интерпретировался в новом свете.
  6. Присутствие такой «созданной» энергии – так называемых вакуумных частиц – было продемонстрировано с помощью эксперимента.