Chapter 1. Electricity in practice (электричество на практике)
Exercise 1. Read and translate the text, using the words below.
The preceding description in terms of fundamental particles and forces is perhaps too theoretical for practical use. What is Electricity in practice?
The tiny imbalance of positive and negative charges discussed above is caused by electrons moving (in enormous numbers at the atomic scale but very tiny numbers percentage-wise) away from the atomic nuclei to which they belong. This motion is perhaps best visualized as a fluid. The hydraulic concepts of fluid flow, pressure, and friction make a good analogy.
In fact, early researchers in electricity in the 18th and 19th centuries saw this, and referred to the "electrical fluid". They even noticed that this "fluid" could be stored in "Leyden jars", which were glass jars with metal foil on the inside and outside. We now know that the jars were just capacitors with the glass as the dielectric, and that the fact that they were jars was a coincidence. We now rate capacitors in farads; early researchers rated them in quarts.
The unit of quantity of electric charge is the coulomb, abbreviated "C", and named after Charles-Augustin Coulomb. There are an enormous number of electrical units, and an enormous number of scientists after whom they are named—Coulomb, Volt, Ampere, Farad, Henry, Gauss, Weber, Tesla, Gilbert, Oersted, Hertz, Siemens, and others. It is 6.241 x 1018 elementary charges. Or equivalently, the elementary charge (charge on a single electron or proton) is 1.602 x 10-19 coulombs. In the hydraulic analogy, it is analogous to a liter of fluid. But unlike water, electric charge can be either positive (deficit of electrons) or negative (excess of electrons.)
Flow of charge—what we call current—could be thought of as flow of positive charge in one direction, or of negative charge in the other direction. By convention, current flow is always considered to be the flow of positive charge, even though that is contrary to the actual flow of (negative) electrons. Hence the current is considered to flow out of the positive terminal of a battery, through whatever is being powered, and back into the negative terminal, even though electron flow through the wires is in the opposite direction.
The unit of current flow is the ampere, abbreviated "A", and which is a flow of one coulomb per second. It is named after André-Marie Ampère. In the hydraulic analogy, it is analogous to the amount of flow through a pipe, or over a dam, etc., which might be measured in liters per second.
Words to be remembered.
bulk–1. масса; основная масса; 2. объём; 3. внутренняя структура (например, проводника)
incredibly–невероятно
capacitor–конденсатор
coincidence–совпадение
convention–собрание; соглашение; обычай
Exercise 2. Answer the following questions.
1. What is electricity from the point of view of atomic physics?
2. What is best visualized as a fluid?
3. What do you know about “Leyden jars”?
4. How do we now rate capacitors and how did the early researches rate them?
5. Can electric charge be positive and negative?
6. What could be thought of as flow of positive charge in one direction, or of negative charge in the other direction?
7. What is the unit of current flow?
Exercise 3. Find the proper Russian equivalents to the given English terms.
| 1. charged particles | 1. крошечный дисбаланс |
| 2. practical level | 2. древние исследователи |
| 3. electron excess | 3. заряженные частицы |
| 4. tiny imbalance | 4. поведение внутренней структуры |
| 5. positive and negative charges | 5. избыток электронов |
| 6. current flow | 6. электрический заряд |
| 7. electrical phenomena | 7. практический уровень |
| 8. electric charge | 8. положит. и отрицат. заряды |
| 9. bulk behavior | 9. поток тока |
| 10. early researches | 10. электрическое явление |
Exercise 4. Translate the following sentences from Russian into English.
1. Фактически, простое электрическое явление возникает из-за невероятно крошечной разницы между количеством положительно заряженных протонов и отрицательно заряженных электронов. 2. Лейденские банки были кувшинами, снаружи и внутри отделанные металлической фольгой. 3. Электрический заряд может быть как положительным, так и отрицательным. 4. Единицей тока является ампер, обозначающийся как «А». 5. Лейденские банки были ни чем иным как конденсаторами, а их стекло служило диэлектриком. 6. Существует огромное количество электрических единиц и большое количество учёных, в честь которых они названы. 7. То, что мы называем током является потоком положительного заряда в одном направлении или отрицательного заряда в другом. 8. С точки зрения атомной физики, электричество – одно из фундаментальных сил природы.
Exercise 5. Make up the outline of the text. Retell the text using your outline.
Exercise 6. Complete the following sentences.
1. Electricity describes the phenomena associated with … 2. The imbalance between photons and electrons … 3. … is caused by electrons moving away from the atomic nuclei to which they belong. 4. … which were glass jars with metal foil on the inside and outside. 5. We now know that the jars were just capacitors with … 6. … electric charge can be either positive or negative. 7. Current flow is always considered to be … 8. … abbreviated “C”, and named after Charles Augustin Coulomb. 9. … is perhaps too theoretical for practical use. 10. There are an enormous number of electrical units, and an enormous number of scientists after whom they are named…
Exercise 7. Match Russian and English terms in columns A and B.
A:particle, excess, tiny, capacitor, coincidence, charge, current, jar, nuclei, bulk
B:избыток, заряд, совпадение, кувшин (банка), ядро, внутренняя структура, частица, крошечный, ток, конденсатор.