2_kurs_4_semestr
.pdf3. After if, we can use were instead of was in all persons. We use If I were you… when we want to give advice.
If I were you, I wouldn‘t spend so much money.
4. We do not usually use will, would or should in an if-clause.
If we take a taxi, we won‘t be late.
NOT If we will take a taxi, we won‘t be late.
However, we use should after if when we are less sure about a possibility.
If I see him, I‘ll give it to him. (Perhaps I will see him.)
If I should see him, I‘ll give it to him. (Perhaps I‘ll see him but I‘m less sure.)
EXERCISES
1. Fill in unless or if.
1) …If… you make so much noise, I won‘t be able to sleep.
2) I won‘t finish the work … you help me.
3) … you‘re hungry, I‘ll make you a sandwich.
4) We‘ll miss the bus … we hurry.
5) You won‘t understand … you listen carefully.
2. |
Match the following parts of the sentences. |
|
1. |
If I go on a diet, |
A. we‘ll make a snowman. |
2. |
If it‘s sunny tomorrow, |
B. I‘ll buy you some chocolate. |
3. |
If John doesn‘t hurry, |
C. she‘ll have to take a taxi. |
4. |
If it snows, |
D. I‘ll lose weight. |
5. |
If there are no buses, |
E. he‘ll be late. |
6. |
If you are a good girl, |
F. we‘ll go for a picnic. |
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3. |
Match the parts of the sentences. |
|
1. |
If I hadn‘t missed the bus, |
A. he would have gone to university. |
2. |
If she hadn‘t felt ill this morning, |
B. Chris wouldn‘t have given me flowers. |
3. |
If the food hadn‘t been awful, |
C. she would have gone to school. |
4. |
If he has passed his exams, |
D. I would have accepted the job. |
5. |
If the salary had been good, |
E. I wouldn‘t have been late for work. |
6. |
If it hadn‘t been my birthday, |
F. we would have eaten it. |
4. Read the sentences and say if they show real or unreal conditions.
1.If it were winter, we should go skiing.
2.If you enter the Teachers‘ Training University, you will become a teacher.
3.If she had had more knowledge, she would have had more chances to enter the university.
4.You might choose something interesting if you had better taste.
5.If you have a headache and your nose is running, I shall call a doctor.
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UNIT 2
Three Kinds of “Radiations”
Read the text and translate it into Ukrainian.
Be ready to describe all the kinds of “radiations”.
Unable to determine the source of the energy directly, turn-of- the-century physicists instead studied the behavior of the ―radiations‖ once they had been emitted. Becquerel had already shown that the radioactivity could penetrate through cloth and paper, so the first obvious thing to do was to investigate in more detail what thickness of material the radioactivity
could get through. They soon learned that a certain fraction of the radioactivity could get through. They soon learned that a certain fraction of the radioactivity‘s intensity would be eliminated by passing through more air.
Apparently, then, the radioactivity was a mixture of more than one type, of which one was blocked by air. They then found that of the part that could penetrate air, a further fraction could be eliminated by a piece of paper or a very thin metal foil. What was left after that, however, was a third, extremely penetrating type, some of whose intensity would still remain even after passing through a brick wall. They decided that this showed there were three types of radioactivity, and without having the faintest idea of what they really were, they made up names for them. The least penetrating type was arbitrarily labeled α
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(alpha), the first letter of the Greek alphabet, and so on through β (beta) and finally γ (gamma) for the most penetrating type.
Alpha – these are fast moving helium atoms. They have high energy, typically in the MeV range, but due to their large mass, they are stopped by just a few inches of air, or a piece of paper.
Beta – these are fast moving electrons. They typically have energies in the range of a few hundred keV to several MeV. Since electrons are might lighter than helium atoms, they are able to penetrate further, through several feet of air, or several millimeters of plastic or less of very light metals.
Gamma - these are photons, just like light, except of much higher energy, typically from several keV to several MeV. X-Rays and gamma rays are really the same thing; the difference is how they were produced. Depending on their energy, they can be stopped by a thin piece of aluminium foil, or they can penetrate several inches of lead.
Identify the types of radiation described here:
1.has no charge
2.has the most mass
3.positively charged
4.most similar to X-rays
5.travels at the speed of light
6.the same as a helium nucleus
Fill in the gaps with the following words:
Air, alpha, cloth, fraction, gamma, intensity, paper, thickness
1.Becquerel had already shown that the radioactivity could penetrate through … and …, so the first obvious thing to do was to investigate in more detail what … of material the radioactivity could get through.
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2.Physicists learned that a certain … of the radioactivity‘s … would be eliminated by passing through more ….
3.The most penetrating type was labeled …, and the least penetrating – … .
Compare three forms of radiation.
Write one complete sentence for each term listed below.
radioactivity |
beta particle |
Geiger counter |
alpha particle |
gamma ray |
cloud chamber |
Individual Work
Radioactivity Detection Devices
1.Find information about the following radioactivity detection devices: electroscopes, Geiger counters, cloud chambers, bubble chambers.
2.Explain how they work (in writing).
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GRAMMAR
0 Conditional. Practice.
EXERCISES
1. Match the items in column A with those in column B in order to make correct Type 0 conditional sentences, as in the example.
e.g. 1-c …If you add sugar to a cup of coffee, the coffee tastes sweeter. …
|
A |
B |
1. |
Add sugar to a cup of coffee. |
a. The apple floats. |
2. |
Throw salt onto snow. |
b. Your skin turns red. |
3. |
Put an apple in a bowl of water. |
c. The coffee tastes sweeter. |
4. |
Water plants regularly. |
d. You feel healthy. |
5. |
Lie in the sun too long. |
e. The plants grow. |
6. |
Take regular exercise. |
f. The snow melts. |
2.Make up 5 sentences using 0 Conditional.
3.Make a zero conditional sentence using the words.
1)ice / float / you / drop / it / in water
2)iron / rust / it / get / wet
3)my daughter / eat / too much chocolate / she /get / sick
4)you / not / eat / you / die
5)if / no / rain / the grass / not / grow
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UNIT 3
The Planetary Model of the Atom
Read the text and translate it into Ukrainian.
Be ready to describe the Rutherford‟s planetary model of the atom.
By 1909, Rutherford was an established professor, and had students working under him. For a raw undergraduate named Marsden, he picked a research project he thought would be tedious but straightforward.
It was already known that although alpha particles would be stopped completely by a sheet of paper, they could pass through a sufficiently thin metal foil. Marsden was to work with a gold foil only 1000 atoms thick.
Rutherford had already determined in his previous experiments the speed of the alpha particles emitted by radium, a fantastic 1.5 × 107 m/s. The experimenters in Rutherford‘s group visualized them as very small, very fast cannonballs penetrating the ―cookie dough‖ part of the big gold atoms. A piece of paper has a thickness of a hundred thousand atoms or so, which would be
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sufficient to stop them completely, but crashing through a thousand would only slow them a little and turn them slightly off of their original paths.
Marsden sat in a dark room, watching the apparatus (shown in the picture) hour after hour and recording the number of flashes with the screen moved to various angles. The rate of the flashes was highest when he set the screen at an angle close to the line of the alphas‘ original path, but if he watched an area farther off to the side, he would also occasionally see an alpha that had been deflected through a larger angle. After seeing a few of these, he got the crazy idea of moving the screen to see if even larger angles ever occurred, perhaps even angles larger than 90 degrees.
The crazy idea worked: a few alpha particles were deflected through angles of up to 180 degrees, and the routine experiment had become an epochmaking one. Rutherford said, ―We have been able to get some of the alpha particles coming backwards. It was almost as incredible as if you fired a 15inch shell at a piece of tissue paper and it came back and hit you.‖
At this point, Rutherford and Marsden dusted off an unpopular and neglected model of the atom, in which all the electrons orbited around a small, positively charged core or ―nucleus‖, just like planets orbiting the sun. All the positive charge and nearly all the mass of the atom would be concentrated in the nucleus, rather than spread throughout the atom as in the raisin cookie model.
The positively charged alpha particles would be repelled by the gold atom‘s nucleus, but most of the alphas would not come close enough to any nucleus to
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have their paths drastically altered. The few that did come close to a nucleus, however, could rebound backwards from a single such encounter, since the nucleus of a heavy gold atom would be fifty times more massive than an alpha particle. It turned out that it was not even too difficult to derive a formula giving the relative frequency of deflections through various angles, and this calculation agreed with the data well enough (to within 15 %), considering the difficulty in getting good experimental statistics on the rare, very large angles.
What had started out as a tedious exercise to get a student started in science had ended as a revolution in our understanding of nature.
Answer the following questions:
1)Who helped Rutherford to develop the planetary model of the atom?
2)What was Marsden to work with?
3)What is the speed of the alpha particles emitted by radium?
4)What has happened when Marsden was watching the apparatus and recording the number of flashes with the screen moved to various angles?
5)Describe the principle of planetary model of the atom.
Match the synonyms. |
|
1. tiny |
a. meet |
2. occur |
b. turn away |
3. various |
c. appear |
4. deflect |
d. small |
5. encounter |
e. different |
Make a plan of the text.
Retell the text. Use your plan.
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GRAMMAR
1 Conditional. Practice.
EXERCISES
1. Match column A with column B in order to make correct type 1 conditional sentences, as in the example.
e.g. If you are tired, go to bed. |
|
Column A |
Column B |
1. tired |
a. make a sandwich |
2. hungry |
b. get something to drink |
3. bored |
c. go to bed |
4. thirsty |
d. take one of these pills |
5. seasick |
e. read a good book |
2. Fill in unless or if.
1.We won‘t go on holiday …unless… we can take our dog with us.
2.… we don‘t buy it now, we‘ll have to get it later.
3.… you go to bed late, you‘ll be tired in the morning.
4.I can‘t finish my homework … you help me.
5.We‘ll have a picnic on Saturday … the weather is bad.
6.You‘ll catch a cold … you wear your coat.
7.I‘ll open the window … I get too hot.
3. Put the verbs in brackets into the correct tense. Add a comma where necessary.
1.If you …have… (have) toothache, go to the dentist.
2.If Peter … (do) lots of exercise he‘ll be fit and healthy.
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