Grammar Exercises (Word Order in a Simple Sentence. Negative Simple Sentence. Word Order in Interrogative Sentences. See appendix, gr. Ref., p. 111-114)

XI. Make up interrogative sentences.

1. A parallel circuit has the main line and parallel branches.

2. The circuit consists of a voltage source, a resistor and a conductor.

3. Switchboard is an assemblage of switches.

4. The capacity of a capacitor is measured in farrads.

5. The sun radiates to our planet great amounts of energy.

6. Test blocks are mounted on the front panel.

XII. Make up special questions to each member of the sentence.

1. Resistors consist of silicon sheet-steel or of special cast iron elements.

2. Many types of oscillator circuits are used nowadays.

3. The experiment was repeated many times.

4. The value of the output depends on the electrolyte of a cell.

5. Aluminium is used in common practice for transmission lines.

XIII. Read the sentences and correct them if the word order is wrong.

1. The Sun our greatest is energy source.

2. The students in the laboratory observed this phenomenon.

3. For peaceful purposes must be atomic energy used.

4. Electric arc is used in electric lamps.

5. A transformer is used energy to transfer.

6. Two diodes in a full-wave rectifier are used.

7. Conductors without a relay with a large cross-section would have to be brought to the motor.

8. Both solid and gaseous insulators are in use highly.

9. There are different types of fuses in use nowadays.

XIV. Translate the following sentences into English paying atten-tion to the word order.

1. Эта статья описывает эксперимент, связанный с электричеством.

2. Главными частями конденсатора являются металлические пласти-ны и изоляторы.

3. Проводники используются для соединения элементов цепи.

4. Существуют два распространенных способа соединения элемен-тов: или параллельно или последовательно.

5. Как результат изменения температуры и влажности, может меняться величина и характеристики некоторых компонентов.

XV. Read text 6 b. Find the answers in the text to the following questions:

1. What is a diode?

2. What’s the main function of a diode?

3. How can one create a diode?

4. What are the uses of a diode?

5. What types of diodes can be distinguished according to the direction of the voltage?

6. Why is it important to choose the diodes?

Text 6 b. Diodes

A diode is a semiconductor device which allows current to flow through it in only one direction. So, what does a diode consist of that lets it operate by this general principle that the current is allowed to flow in one direction but not the other? Let’s consider the process of creating a typical P-N junction diode. When you put N-type and P-type silicon together as shown in this diagram, you get a very interesting phenomenon that gives a diode its unique properties.

Even though N-type silicon by itself is a conductor, and P-type silicon by itself is also a conductor, the combination shown in the diagram doesn’t conduct any electricity. The negative electrons in the N-type silicon are attracts to the positive terminal of the battery. The positive holes in the P-type silicon are attracted to the negative terminal of the battery. No current flows across the junction because the holes and the electrons one each moving in the wrong direction.

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If you slip the battery around, the diode conducts electricity just fine. The free electrons in the N-type silicon are repelled by the negative terminal of the battery. The holes in the P-type silicon are repelled by the positive terminal. At the function between the N-type and P-type silicon, holes and free electrons meet. The electrons fill the holes. Those holes and free electrons cease to exist, and new holes and electrons spring up to take their place.

The effect is that current flows through the junction. A device that blocks the current in one direction while letting the current flow in another direction is called a diode.

Diodes can be used in a number of ways, for example:

– a diode can be used as a rectifier that converts AC (Alternating Current)

to DC (Direct Current) for a supply device;

– diodes can be used to separate the signal from radio frequencies;

– diodes can be used as an on/off switch that controls current.

When a small voltage is applied to the diode in a forward direction, current flows easily. Because the diode has a certain amount of resistance, the voltage will drop slightly as the current flows through the diode. When voltage is applied in the reverse direction through a diode, the diode will have a great resistance to the current flow. Different diodes have different characteristics when reversed-biased. This diode should be selected depending on how it’ll be used in the circuit.

The limiting voltages and currents permissible must be considered on a case by case basis. For example, when using diodes for rectification, part of the time they will be required to withstand a reverse voltage. If the diodes are not carefully, they will break down.