UNIT 17

 

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

 

to ionize, to penetrate, span, upward, reveal, potential, to rotate, voltage, to insulate, shield, lead, cancer, ionic, concrete, flaw, ultimate, thorium, to overlap

 

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

 

Text: “X-Rays and Gamma-Rays”.

 

The part of the electromagnetic spectrum with very short wavelengths (between about 10^-9 m and 10^-15 m) and very high frequencies corresponds to X-rays and gamma rays. Both are high-energy, penetrating types of radiation that can ionize gasesand cause other chemical and physical changes, such as fluorescence.

X-rays. X-rays are one of the types of radiation emitted by some stars and galaxies. Studies of heavenly bodies from artificial satellites have revealed various X-ray sources, among which are possible locations of black holes. The observations have to be made from space because X-rays do not pass through the atmosphere (although highly energetic, X-rays do not penetrate the atmosphere because they interact with molecules in the air). Here on earth, X-rays are generated artificially.

X-rays are produced using thermionic vacuum tubes that operate at potentials of up to 2 million volts. A stream of electrons, fired from the cathode of the tube, strikes a metal anode (the target), which emits X-rays. The X-ray beam is emitted at right angles to the electron beam. Because of the high voltage necessary and the penetrating power of the radiation itself, commercial X-ray machines are heavily insulated and shielded with lead, which absorbs X-ray.

The best-known uses of X-rays are in medicine: in radiology to “photograph” the internal structures of the body and in radiotherapy for destroying cancerous tumors. X-rays are also used extensively for internal examination of industrial materials, for example in the detection of flaws and other weaknesses in metal castings and welds.

Gamma rays. During the radioactive decay of unstable isotopes of elements, such as uranium, thorium, and radium, gamma rays are emitted. These constitute electromagnetic radiation of extremely short wavelength, from about 10^-10 m down to 10^-15 m or less, overlapping to some extent with those of “hard” X-rays. The main difference between the twotypes of radiation is in their origins. X-rays are produced by bombardment of atoms with high-energy electrons, which cause excitation of the atomic electrons. Gamma rays derive from the excitation of the atomic nucleus itself. In both cases, characteristic radiation is emitted when the excited electrons or nucleons return to their original energy levels.

The properties of gamma rays resemble those of X-rays. Like X-rays, gamma rays can be used to reveal flows in solid materials; a suitable source for such applications is cobalt-60 or some other long-lived radioisotope. In research into particle physics, gamma rays often occur as product of collisions between high-energy subatomic particles. They are, therefore, important in the study of the ultimate structure of matter.

 

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

 

1. X-rays are one of the types of radiation emitted by some stars and galaxies.
2. X-rays were found to produce strong ionization in gases.
3. X-rays are produced when the fast moving electrons of the cathode stream are suddenly stopped.
4. The X-ray beam is emitted at right angels to the electron beam.
5. The main difference between the two types of radiation is in their origins.
6. Gamma rays do not carry a charge of electricity and are not deflected by either an electric or a magnetic field.
7. The properties of gamma rays resemble those of X-rays.

 

IV. Find English equivalents in the text.

 

1. высокие частоты ___________________________________________
2. вызывать химические и физические изменения ________________
3. искусственно ______________________________________________
4. взаимодействуют с молекулами ______________________________
5. электронная лампа _________________________________________
6. поток электронов __________________________________________
7. высокое напряжение _______________________________________
8. широко используются для внутреннего исследования __________
9. литье _____________________________________________________
10. сварной шов _______________________________________________
11. радиоактивный распад _____________________________________
12. неустойчивый изотоп _______________________________________
13. исходные энергетические уровни _____________________________
14. нуклон ____________________________________________________
15. радиоизотоп с большим периодом полураспада ________________
16. физика элементарных частиц ________________________________

 

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

 

1. the electromagnetic spectrum with very short wavelengths ______________
2. penetrating types of radiation ______________________________________
3. studies of heavenly bodies have revealed ____________________________
4. are generated artificially __________________________________________
5. at potentials of up to 2 million volts ________________________________
6. is emitted at right angles _________________________________________
7. are heavily insulated and shielded __________________________________
8. the internal structures of the body __________________________________
9. the detection of flaws ____________________________________________
10. overlapping to some extent _______________________________________
11. high-energy electrons ____________________________________________
12. cause excitation of the atomic electrons _____________________________
13. occur as a product of collision _____________________________________
14. ultimate structure of matter _______________________________________

 

VI. Analyze the structure of the sentence.

 

1. The observations have to be made from space because X-rays do not pass through the atmosphere.
2. X-rays are produced by bombardment of atoms with high-energy electrons, which cause excitation of the atomic electrons.

 

VII. Fill in the missing words.

 

1. The part of the electromagnetic spectrum with very short _____ and very high _____ corresponds to X-rays and gamma rays.
2. Both are high-energy, penetrating types of radiation that can _____ gases and cause other chemical and physical changes, such as _____.
3. Studies of heavenly bodies from _____ _____ have revealed various X-ray _____.
4. Here on earth, X-rays are _____ artificially.
5. Commercial X-ray machines are heavily _____ and _____ with lead, which absorbs X-ray.
6. The main difference between the two types of radiation is in their _____.
7. Gamma rays _____ from the excitation of the atomic nucleus itself.
8. Like X-rays, gamma rays can be used to _____ flows in solid materials.
9. In research into particle physics, gamma rays often occur as product of _____ between high-energy subatomic particles.

 

VIII. Fill in the prepositions if necessary.

 

1. X rays are one ___ the types ___ radiation emitted ___ some stars and galaxies.
2. The observations have to be made ___ space.
3. Here ___ earth, X-rays are generated artificially.
4. A stream ___ electrons, fired ___ the cathode ___ the tube, strikes ___ a metal anode, which emits X-rays.
5. The X-ray beam is emitted ___ right angles ___ the electron beam.
6. Because ___ the high voltage necessary and the penetrating power ___ the radiation itself, commercial X-ray machines are heavily insulated and shielded ___ lead.
7. X-rays are produced ___ bombardment ___ atoms ___ high energy electrons, which cause excitation ___ the atomic electrons.
8. Gamma rays derive ___ the excitation ___ the atomic nucleus itself.
9. Like X-rays, gamma rays can be used to reveal flows ___ solid materials; a suitable source ___ such applications is cobalt-60 or some other long-lived radioisotope.
10. They are, therefore, important ___ the study ___ the ultimate structure ___ matter.

 

IX. Define whether the sentences are true or false.

 

1. X-rays and gamma rays are high-energy, penetrating types of radiation that can ionize gases and cause other chemical and physical changes, such as fluorescence.
2. Studies of heavenly bodies from artificial satellites haven’t revealed any X-ray sources.
3. The X-ray beam is emitted at obtuse angles to the electron beam.
4. Because of the high voltage necessary and the penetrating power of the radiation itself, commercial X-ray machines are heavily insulated and shielded with lead, which absorbs X-rays.
5. The best-known uses of X-rays are in chemistry.
6. The main difference between the two types of radiation is in their properties.
7. In research into particle physics, gamma rays often occur as product of collisions between low-energy subatomic particles.

 

X. Practice with someone asking and answering.

 

1. What does the part of the electromagnetic spectrum with very short wavelengths and very high frequency correspond to?
2. What can X-rays and gamma rays cause?
3. What have studies of heavenly bodies from artificial satellites revealed?
4. Why do the observations have to be made from space?
5. How are X-rays produced?
6. Why are commercial X-ray machines heavily insulated and shielded with lead?
7. In what spheres are the best-known uses of X-rays?
8. When are gamma rays emitted?
9. What is the main difference between two types of radiation?
10. What do the properties of gamma rays resemble?
11. Are gamma rays important in the study of the ultimate structure of matter?

 

XI. Put questions to the following sentences.

 

1. X-rays are one of the types of radiation emitted by some stars and galaxies. (General)
2. Studies of heavenly bodies from artificial satellites have revealed various X-ray sources, among which are possible locations of black holes. (General)
3. Here on earth, X-rays are generated artificially. (Disjunctive)
4. The X-ray beam is emitted at right angles to the electron beam. (Alternative)
5. X rays are produced by bombardment of atoms with high-energy electrons. (Special)
6. Gamma rays derive from the excitation of the atomic nucleus itself. (General)
7. Characteristic radiation is emitted when the excited electrons or nucleons return to their original energy levels. (Special)
8. Gamma rays often occur as product of collisions between high-energy subatomic particles. (Disjunctive)

 

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

 

1. X-rays are one of the types of radiation emitted by some stars and galaxies.
2. X-rays are produced using thermionic vacuum tubes that operate at potentials of up to 2 million volts.
3. The X-ray beam is emitted at right angles to the electron beam.
4. The main difference between the two types of radiation is in their origins.
5. The properties of gamma rays resemble those of X-rays.
6. In research into particle physics, gamma rays often occur as product of collisions between high-energy subatomic particles.

 

XIII. Dictation-translation.

 

1. Часть электромагнитного спектра с очень короткими длинами волн и очень высокими частотами соответствует рентгеновскому излучению и гамма излучению.
2. Наблюдения должны проводиться из космоса потому, что рентгеновские лучи не проходят через атмосферу.
3. Во время радиоактивного распада неустойчивых изотопов таких элементов как ураний, торий и радий происходит гамма-излучение.
4. Рентгеновское излучение вырабатывается посредством бомбардирования атомов высокоэнергетическими электронами, что вызывает возбуждение электронов атома.
5. Гамма лучи получаются от возбуждения самого ядра.
6. Свойства гамма лучей походят на свойства рентгеновских лучей.