Exercise 2. Use the notes given below to write a description of three types of rays.
Alpha-rays
positively charged particles
the velocity about
1/10 that of light
to be absorbed by thin foil
to affect a photographic plate
to cause bodies to fluoresce
to ionize the air
to be deflected by an electric and magnetic field
Beta-rays
negatively charged particles
the velocity is not as great as that of light
much more penetrating
to be less active photographically
to produce less ionization
to be deflected in an electric or magnetic field
Gamma-rays
electromagnetic pulses
extremely penetrating
to be unaffected by electric or magnetic fields
Reading 3-C
The Discovery of Radioactivity
The existence of penetrating radiation that could pass through layers of opaque materials as if they were made of clear glass was а recognized fact at the time of Becquerel's discovery. In fact, only а year earlier (1895) а German physicist Wilhelm Roentgen (1845-1923), discovered X-rays, which can penetrate equally well through cardboard, black paper, or the human body. But there was an important difference between the rays discovered by Becquerel and the X-rays. While special equipment was required to produce X-rays, the radiation discovered by Becquerel was flowing from the piece of uranium ore without any external excitation. It was Marie Curie who invented the term ‘radioactive’ to describe a substance that gave out these new rays all the time. The early studies of the newly discovered phenomenon which was called radioactivity showed that the emission of mysterious radiation was completely unaffected by physical or chemical conditions.
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It was soon found that this property of emitting penetrating radiations was not confined to uranium and its compounds. Thorium and its compounds and minerals containing thorium have this same property. Such substances are said to be radioactive. Ву studying the radioactive mineral called pitchblende (урановая смолка) which contained uranium and thorium Pierre and Marie Curie found that this mineral contained substances which were much more radioactive than either uranium or thorium. The Curies finally isolated two new elements. Marie called the first one ‘polonium’ after Poland, where she was born. The second one was called ‘radium’ because it was highly radioactive.
Exercise 1. Use Reading 3-C to find the English equivalents for the following Russian phrases.
Существование проникающего излучения; признавать - признанный факт; требовать специального оборудования; без внешнего возбуждения; ограничиваться соединениями урана; не зависеть от физических и химических условий; обладать таким же свойством; выделить новый элемент; как уран, так и торий; либо уран, либо торий; ни уран, ни торий.
Exercise 2. Summary writing. Answer the questions below and write down your answers. You will get thirteen simple sentences.
1.Was penetrating radiation quite a new phenomenon at the time of Becquerel or was it a recognized fact?
2.Were X-rays discovered by Roentgen a year earlier?
3.Can X-rays discovered by Roentgen penetrate through opaque substances easily?
4.Is there a difference between X-rays and the rays discovered by Becquerel?
5.Do X-rays require special equipment?
6.Do Becquerel’s rays flow spontaneously from a piece of uranium ore?
7.Was the emission of mysterious radiation completely unaffected by physical or chemical conditions?
8.Is the spontaneous radiation confined to uranium compounds?
9.Do thorium compounds have the same property?
10.Did the Curies study pitchblende?
11.Is pitchblende a mixture of uranium and thorium?
12.Did they isolate new highly radioactive substances?
13.Did they call them polonium and radium?
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Combine the sentences to make five complex sentences and write them as a paragraph. You can join the simple sentences in the following way:
1.Join 1 and 2 by means of «in fact».
2.Join 3 and 4 by «however».
3.Join 5 and 6 by «while».
4.Join 6 and 7 by «therefore», «thus» or «so».
5.Join 8 and 9 by «as».
6.Join 10 and 11 by «which».
7.Begin 12 with «As a result…»
8.Join 12 and 13 by «which».
Do you know?
Pitchblende is an old name for uraninite, which is uranium ore mineral, basically uranium oxide. Pitchblende is also the rock in which Marie Curie discovered radium.
Pitchblende was first discovered in the silver mines of St. Joachimsthal (now the Czech Republic), as a material that accompanied rich silver deposits. «Pitchblende» comes from the German word «pechblende». The German word «blende» means «mineral», while «pech» means «bad luck», so it was literally the «bad-luck-mineral».
Seeing this mineral was never welcome: it usually meant that there was no more silver left in the mine and that miners would have to work hard to start a new one. Pitchblende was useless at the time it was named. That was because nobody had a use for uranium at the time.
The town of Joachimsthal is also known to have given its name to the U.S. dollar. In the 16th century, the silver mined there was used to produce coins, which were called «Joachimsthalers». The name was later shortened to «thalers» (талеры), and then changed into «dollars» in English-speaking countries.
Isn't it ironic that a small town in the Czech Republic gave us the two things that shaped the modern world? Both have changed, and continue to affect our lives, our politics and international relations.
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Reading 3-D
How Dangerous is Radiation?
Background radiation is that which is naturally and inevitably present in our environment. It is all around us, all the time. Our bodies are exposed to natural radiation every day -- from soil and underground gases to cosmic radiation from the sun and outer space. But radiation is not always dangerous. It depends on its strength, type and the length of exposure.
Radiation comes in many forms and can be either ionizing or nonionizing. Ionizing radiation changes the physical state of atoms and
causes them to become electrically charged or “ionized”. This means that when ionizing radiation passes through the body, it actually has enough energy to damage DNA and cause various diseases. Ionizing radiation is both natural and man-made. Some of the natural sources of ionizing radiation are naturally-occurring radionuclides in the earth, building materials, air, food and water, and cosmic rays. Medical and dental X-rays, smoke detectors and radionuclides emitted from nuclear power plants are good examples of man-made ionizing radiation. Overexposure to ionizing radiation can cause mutations in genes, which causes birth defects, a high risk of cancer, burns or radiation sickness.
Non-ionizing radiation does not have enough energy to ionize atoms or molecules. It consists of electromagnetic radiation ranging from the extremely low frequency (ELF) to the ultraviolet (UV). Non-ionizing radiation sources include microwaves, radio waves, infrared radiation, visible light and lasers. We are constantly exposed to non-ionizing radiation from our own inventions – power lines, cell phones and microwave ovens. Although considered less dangerous than ionizing radiation, overexposure to non-ionizing radiation can cause health problems.
Living things have evolved in an environment which has significant levels of ionizing radiation. Furthermore, many of us owe our lives and health to such radiation produced artificially. Ionizing radiation is used to diagnose diseases, and some people are treated with radiation to cure diseases. We all benefit from a great number of products and services made possible by the careful use of radiation.
Exercise 1. Translate the following noun groups.
Background radiation, uranium compounds, fluorescence phenomenon, reactor accident, mineral properties, metal sheets, radiation emission,
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radiation exposure, energy waves, decay process, energy transformation, isotope disintegration, radioactivity level, isotope half-life, gas ionization.
Exercise 2. What do the following abbreviations stand for? Refer to the dictionary or other sources if you do not know the answer.
ELF, UV, DNA, REM, Bq, Ci, laser.
Exercise 3. Give the derivatives of the words below.
1.Ground – фон.
2.Present – присутствие.
3.To expose to – воздействие, чрезмерное воздействие.
4.Danger – опасный.
5.Strong – интенсивность, сила.
6.Ion – ионизировать, ионизация, ионизирующий.
7.To vary – разнообразный, переменный.
8.Nature – естественный, естественно.
9.To detect – обнаружение, детектор.
10.Frequency – частый, часто.
11.To evolve – эволюция.
12.Sign – сигнал, значительный, конструировать.
13.Art – искусственный.
14.To benefit – полезный.
Exercise 4. Use Readings 3-A, 3-B, 3-C and 3-D to find definitions for the terms below.
Radioactivity, radiation, radioactive substances, radioactive decay, half-life, alpha-rays, beta-rays, gamma-rays, pitchblende, background radiation, ionizing radiation, non-ionizing radiation.
Exercise 5. Discuss with your group one of the topics listed below.
1.Is background radiation dangerous?
2.Sources of natural and man-made background radiation.
3.Difference between ionizing and non-ionizing radiation.
4.Risks and benefits of ionizing radiation.
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