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

III. Find an adverb in each line and translate it. Translate also the underlined words.

a) Conclude, motion, traditionally, unique, encourage.

b) Probability, unstable, conclude, gradually, fraction.

c) Exchange, abroad, observation, tiny, occur.

d) Certainty, widely, inaccurate, frequency, prove.

e) Influential, co-worker, chemical, properly, distinguish.

f) Strongly, subatomic, apply, success, urge.

IV. Practice the following speech patterns.

Pattern 1. Bohr developed basic ideas about the structure of an atom.

1. Newton – the motion of bodies.

2. Einstein – space-time continuum.

3. Max Planck – the atom and its motion.

4. Ernest Rutherford – radioactivity.

5. James Clerk Maxwell – electromagnetism.

6. Galileo – the solar system.

7. Michael Faraday – electrical induction.

Pattern 2. Bohr claimed that an atom exists in a series of stable states.

1. Ernest Rutherford – atoms can disintegrate.

2. J. J. Thomson – electrons are a fundamental part of all matter.

3. Max Planck – radiant energy is a stream of quanta of energy.

Pattern 3. Bohr based this theory on observations of the spectrum of light.

1. Newton – movements of planets

2. Joseph J. Thomson – cathode rays.

3. Michael Faraday – the electric current.

V. Find the sentences that can’t be found in the text.

1. Bohr developed basic ideas about the structure of an atom.

2. Bohr’s work contributed strongly to most of the important discoveries in physics during and since his lifetime.

3. Bohr, along with other distinguished physicists of the early 1900’s, developed a new branch of physics known as quantum mechanics.

4. Albert Einstein, Max Planck, Niels Bohr, and other developed the theories of quantum mechanics in the early 1900’s to better describe the atom and its motion.

5. He claimed that an atom exists in a series of stable states.

6. Bohr based this theory on observations of the spectrum of light that the element hydrogen gives off.

7. Bohr thought that the band of light frequencies given off by a chemical element could only be explained by the theory of «quantum jumps» of energy in the atom.

VII. Find Uzbek equivalents to the following words and expressions in the text.

1. the ideas have been widely accepted _______________________

2. along with other distinguished physicists ___________________

3. with the movements of planets in mind _____________________

4. probed deeper into the atom _____________________________

5. an accurate model for atomic motion ______________________

6. a stream of bundles of energy ____________________________

7. probabilities _________________________________________

8. a quantum jump ______________________________________

9. happens in a fraction of time _____________________________

10. band of light frequencies _______________________________

11. welcomed the exchange of ideas _________________________

12. earned the respect ___________________________________

VIII. Analyze the structure of the following sentences.

1. These speculations led physicists to conclude that atomic particles, such as electrons, have properties of both particles and waves.

2. No longer could scientists calculate with certainly the position of an electron in its orbit at a particular moment.

3. Bohr thought that the band of light frequencies given off by a chemical element could only be explained by the theory of «quantum jumps» of energy in the atom.

4. Scientific observations made during and after his lifetime have proved his theory true.

IX. Fill in the missing words.

1. Niels Bohr was one of the greatest and most ______ scientists of the twentieth century.

2. For his important work, Bohr was ______ the Nobel Prize in _______ in 1922.

3. Bohr developed a new branch of physics known as ________ mechanics.

4. As physicists _______ deeper into the atom, however, they gradually realized that the solar system is not an ________ model for atomic motion.

5. One idea is that radiation – such as light – is emitted in a stream of separate ________ of energy called quanta.

6. This idea came to be known as the «_______ _______ duality» principle.

7. Such movements, according to quantum mechanics, can be mathematically described only as _________.

8. Niels Bohr ________ these ideas further.

9. Between such states, a ________ in energy level ________ in the atom.

10. With every quantum jump, light photons are ________ ________.

X. Fill in the prepositions if necessary.

1. Bohr developed basic ideas ___ the structure ___ an atom.

2. ___ his important work, Bohr was awarded the Nobel Prize ___ physics ___ 1922.

3. The laws ___ motion and gravity formulated ___ Newton ___ the 1600’s could not explain motion ___ the atomic level.

4. Newton had developed his physics ___ the movements ___ planets ___ mind.

5. No longer could scientists calculate ___ certainly the position ___ an electron ___ its orbit ___ a particular moment.

6. The jump can be ___ a higher energy level or ___ a lower energy level.

7. ___ every quantum jump, light photons are given ___.

8. Bohr based this theory ___ observations ___ the spectrum ___ light that the element hydrogen gives ___.

9. The reason ___ this influence went ___ Bohr’s own contribution ___ physics.

10. The institute owned much ___ its success and influence ___ its director.

XI. Practice with someone asking and answering.

1. What was Niels Bohr?

2. What ideas did Bohr develop?

3. Was Bohr awarded any prize for his work?

4. What branch of physics did Bohr develop?

5. Why couldn’t the laws of motion and gravity formulated by Sir

Isaac Newton properly explain motion at the atomic level?

6. When did physicists realize that the solar system was not an

accurate model for atomic motion?

7. Why did Albert Einstein, Max Planck, Niels Bohr and others

develop the theories of quantum mechanics?

8. What important principle was formulated in connection with the

theories of quantum mechanics?

9. How can the movements of an electron in its orbit be mathemat-

ically described?

10. What did Niels Bohr claim?

11. What did Bohr base his theory on?

12. Why did he earn the respect of fellow scientists?

XII. Translating in Uzbek without using a dictionary.

Bohr appreciated friendly disagreements in science. Niels Bohr was born in Copenhagen, Denmark, in 1885. His father was a famous professor at the University of Copenhagen. His mother was from a family that had been important in banking and in government. The Bohr children were encouraged to excel in their studies. Niels’s brother, Harald, became a brilliant mathematician. Niels attended the University of Copenhagen, where he won a gold medal from the Royal Danish Academy of Sciences and Letters for original scientific research. In 1911 he went to England to study with the great physicist Sir J.J.Thomson at Cambridge University. The next year he went to the University of Manchester, where he studied with Ernest Rutherford. At this time, Rutherford was developing his nuclear model of the atom. Rutherford’s ideas profoundly affected Bohr and led to the younger man’s own landmark theories. In 1912 Bohr returned to Copenhagen. Eventually he became a professor at the University of Copenhagen and director of the Institute of Theoretical Physics. During the 1920’s and 1930’s, Bohr exchanged ideas with most of the physicists of the time and travelled widely. This creative and satisfying period came to an abrupt end in 1940 when Nazi Germany invaded and occupied Denmark. Bohr and his family escaped to Sweden in a fishing boat. Later Bohr and his son went to England, where they worked on projects to develop a nuclear fission bomb. This research eventually led Bohrs, father and son, to the Los Alamos, New Mexico, laboratory that made the first practical atomic bomb in 1945. Meanwhile, Bohr had become deeply worried about the dangers of the atomic weapon upon which he was working. He talked to both President Roosevelt and Prime Minister Churchill about the need for international atomic cooperation.Bohr also promoted such postwar international efforts as the First International Conference on the Peaceful Uses of Atomic Energy (Geneva, Switzerland, 1955). He also helped create the European Counci for Nuclear Research (CERN). For these efforts, Niels Bohr received the first U.S. Atoms for Peace Award in 1957. When Bohr died in 196 he was widely recognized as one of the greatest scientists, public figures, and peace advocates of his time.

UNIT 13

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

Relating to, unique, spectrum (spectra), generation, concept,

quantum (quanta), to reveal, to deal with, to exist, to absorb, to emit,

state, frequency.

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

TEXT: «ATOMIC STRUCTURE AND QUANTUM THEORY»

At the turn of the 20 th century, physicists spent much effort in trying to derive all the observed phenomena relating to elements from a mathematical model of the atom. One key phenomenon was the spectral lines produced by atoms on being heated: each element has its own unique atomic spectrum. In trying to explain the generation and appearance of atomic spectra, physicists found that they had to introduce the concept of quantum. Close scrutiny of a black-and-white newspaper photograph reveals that the apparent differences in light and dark tones are not the result of gradual shading but rather are created by subtly different sizes of dots, or «packets» of ink on the plain paper. Physicists have discovered that, in dealing with matter on the smallest scale, even energy must be treated as existing in «packets» or quanta, and not as being continuous. The quantum concept provides the key to understanding how atoms can absorb and emit energy, and how the various atomic spectra are produced. In a simple quantum-based visualization of the atom, the electrons orbit the central nucleus like planets in a miniature solar system. The electrons can move only in certain orbits about the nucleus. By giving up that energy, they drop back into the original lower orbits (called the ground state). With each energy change, radiation of a particular frequency is absorbed or emitted. From this analysis, the origin of atomic spectra can be explained. The individual spectral lines (of certain frequencies) represent electrons falling from high-energy excited states back to their low-energy ground states. As they do so, they emit quanta of radiation (photons).

III. Put the sentences in the right order.

1. In an atom the electrons orbit the central nucleus like planets in a miniature solar system.

2. In trying to explain the generation of atomic spectra, physicists introduced the concept of quantum.

3. The individual spectral lines represent electrons falling from high-energy excited states back to their low energy ground states.

4. At the beginning of the 20 th century scientists tried to derive all the observed phenomena from a mathematical model of the atom.

5. The quantum concept provides the key to understanding how atoms can absorb and emit energy.

IV. Translate the following noun groups into Uzbek.

1. key phenomenon;

2. energy change;

3. the appearance of spectra;

4. the concept of quanta;

5. the study of a photograph;

6. different sizes of dots;

7. «packets» of ink;

8. a visualization of the atom;

9. a miniature solar system;

10. radiation of a particular frequency

11. the origin of atomic spectra;

12. quanta of radiation.

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

1. spent much effort;

2. its own unique atomic spectrum;

3. in dealing with matter on the smallest scale;

4. the result of gradual shading;

5. the concept of quantum;

6. the quantum concept;

7. the ground state

8. emit quanta of radiation.

VII. Practice with someone asking and answering.

1. When did physicists spend much effort in trying to derive all the observed phenomena from a mathematical model of the atom?

2. What was one of the key phenomena?

3. What concept did physicists have to introduce?

4. What does close scrutiny of a black-and-white newspaper photograph reveal?

5. What is a simple quantum-based visualization of the atom?

6. Can the electrons move randomly or in certain orbits?

7. What happens to the electrons when they give up the energy?

8. What do individual spectral lines represent?

VIII. Dictate the following sentences in English to your fellow-students. Check them together.

1. The quantum concept provides the key to understanding how atoms can absorb and emit energy.

2. The electrons orbit the central nucleus like planets in a miniature solar system.

3. The electrons can move only in certain orbits about the nucleus.

4. By giving up the energy, they drop back into the original lower orbits.

5. With each energy charge, radiation of a particular frequency is absorbed or emitted.

6. From this analysis, the origin of atomic spectra can be explained.

IX. Put special questions to the following sentences.

1. At the turn of the 20 th century physicists spent much effort trying to understand atomic structure. (When ...?)

2. Close scrutiny of a newspaper photograph reveals that the differences in light and dark tones are created by different sizes of dots on the paper. (What ...?)

3. The electrons orbit the central nucleus like planets in a miniature solar system. (How ...?)

4. In trying to explain the appearance of atomic spectra, physicists introduced the concept of quantum. (Why ...?)

5. The electrons can move only in certain orbits about the nucleus.(How ...?)

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 Uzbek.

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.

V. Find Uzbek 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.

UNIT 15

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

to constitute, frequency, to identify, to exhibit, reflection, re-

fraction, dispersion, opaque, to encounter, matte, to absorb, to ob-

tain, surface, concave, convex, the angle of incidence, image

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

TEXT: «LIGHT AND REFLECTION»

Visible light constitutes only a very small part of the electromagnetic spectrum of wavelengths, just over a hundred-thousandth of an inch long. The longest visible wavelengths (lowest frequencies) are seen as red light, the shortest (highest frequencies) as violet. Various other colors can be identified between these two extremes. Conventionally, the spectral colors are red, orange, yellow, green, blue, indigo, and violet. Being a form of electromagnetic radiation, visible light exhibits all the properties characteristic of such radiation – for example, wave-particle (photon) duality, reflection, refraction, diffraction, dispersion, interference, and polarization. Light waves travel outwards in all directions from their source, thereby forming an expanding spherical wavefront. Each individual wave travels in a straight line in a vacuum, or in any isotropic medium (one with uniform properties throughout). As light travels in straight lines, shadows are formed behind opaque objects. If the light source is very small, effectively a point source, the entire shadow is equally dark and has well-defined edges. If, on the other hand, the source is relatively large – which is usually the case – the shadow is blurred at the edges and has a dark central region of complete shadow (called the umbra) surrounded by a region of partial shadow (the penumbra), which is illuminated by light from part of the source. Reflection. All objects and surfaces encountered in everyday life reflect light. That is why they are visible. Only a perfectly matte, black surface absorbs all light, and such a surface is extremely difficult to obtain. Many surfaces reflect only light of certain wavelengths, and so they appear colored when illuminated with light, which contains all visible wavelengths. The nature of the surface also affects the type of reflection. Irregular surfaces and smooth, matte ones reflect light randomly and so cannot form images. For example, the pages of the book reflect light randomly, so enabling the type to be read rather than reflecting an image of the reader. Very smooth, shiny surfaces on the other hand, reflect light in a regular way and these types of «mirror» surfaces can therefore form well-defined images. Mirrors and images. There are three main types of mirrors: plane, concave, and convex. Plane mirrors are flat and are the most familiar type. Concave mirrors are hollowed – shaving mirrors are an example. And convex mirrors bulge outwards – they are used for some driving mirrors, for instance, because they give a wide angle of view. Reflection in all three types of mirrors is governed by two principal laws. The first law of reflection states that the incident ray (or beam) striking the surface and the reflected ray (or beam) leaving it are in the same plane as the normal (an imaginary line perpendicular to the surface at the point where the incident ray hits it). The second law of reflection states that the angle of incidence (between the incident ray, or beam, and the normal) is equal to the angle of reflection (between the reflected ray, or beam, and the normal). Using these two laws it is possible to determine the types of images formed by the different sorts of mirrors.

III. Find the sentences that can’t be found in the text.

1. The surface of still water can act as an almost perfect mirror.

2. In fact, the only difference among images formed by a convex mirror is their degree of diminution.

3. The farther the object is from the mirror, the smaller is the image.

4. The spectral colors are red, orange, yellow, green, blue, indigo and violet.

5. The nature of the surface also affects the type of reflection.

6. As the object is moved nearer the mirror, the image becomes larger.

7. Moving the object just inside the focus produces an upright, much magnified virtual image.

8. The image formed by a plane mirror is the same size as the object.

V. Find Uzbek equivalents to the following expression in the text.

1. electromagnetic spectrum of wave lengths __________________

2. to exhibit the properties ________________________________

3. diffraction __________________________________________

4. all surfaces encountered in everyday life ____________________

5. they appear coloured when illuminated _____________________

6. irregular surfaces _____________________________________

7. to reflect light randomly _______________________________

8. to reflect light in a regular way __________________________

9. well-defined images ___________________________________

10. plane mirrors ________________________________________

11. the incident ray ______________________________________

12. to determine the types of images _________________________

VI. Fill in the missing words.

1. Visible light constitutes only a very small part of the _______ _______of wavelengths.

2. Conventionally, the spectral colours are listed as red, orange, _______, _______, _______, _______ and violet.

3. Visible light exhibits all the _______ characteristic of electromagnetic radiation.

4. All objects and surfaces _______ in everyday life _______ light.

5. Only a perfectly matte, black surface _______ all light.

6. The nature of the surface _______ the type of reflection.

7. Irregular surfaces reflect light _______.

8. Very smooth, shiny surfaces reflect light _______.

9. There are three main types of mirrors: _______.

10. Reflection in all three types of mirrors _______ by two principal laws.

11. The first law of reflection states that the incident ray _______ the surface and the reflected ray _______ it are in the same plane as the normal.

12. The second law of reflection states that _______ is equal to the angle of reflection.