Put questions to each other.

4. Summarize the general ideas of the text. Use the following plan:

а) The first diodes and types of radio signals in them.

b) The substances making some sections more resistant to electrical flow than others.

c) The boundary between sections of different purity that makes the crystal work.

d) Functioning of different types of semiconductors.

e) Different types of electron's moving.

5. Define the forms and the functions of Participle:

1)Having spent several days trying to assemble the machine, his efforts came to nothing.

2) Installed, the wire may be used as a conductor.

3) The engine tested required further improvement.

4) A valve when used in this manner is called a photoelectric tube.

5) The instruments get spoilt if left in the open air.

6) Having discussed all the advantages and disadvantages of the direct current system we spoke in its favour.

7) The instrument designed by this engineer arrived just in time.

8) Having determined the condenser's type students used the latter in the experiment.

9) The isolated product was obtained.

10) This reaction was stopped having given poor results.

11) Data provided vary with the purpose and scope of each particular investigation.

12) This allows the reactions described here to occur at higher temperatures.

13) Having been determined the capacitors of this type should be treated carefully.

14) While heated magnetized steel will lose its magnetism because of rapid motion of molecules.

15) Having improved this device they could use it for many purposes.

16) Having been given all the instructions the machine made all calculations.

6. Underline the Absolute Participial Construction and translate the sentences:

l) With the experiments having been carried out, we started new investigations.

2) The temperature of the melted ice rising, the movement of its molecules is speeded up.

3) The time of the beam's travel and its velocity being known, the scientists were able to calculate the distance to different parts of the Moon's surface with great precision.

4) Current passing through a coil of wire, magnetic poles are produced at each end of the coil and its acts like a magnet.

5) Different type of contact materials for current collectors having been discussed, engineer chose steel and copper as being the best.

6) Computers and calculating machines can be subdivided into two classes: analogue and digital, the basic distinction being the way in witch numbers are represented inside the machine for purposes of calculating.

7) Parts of the energy being changed into heat, not all the chemical energy of the cell battery is transformed into electric energy.

8) Time permitting, they will discuss the matter tomorrow.

9) A magnetic field surrounds a current-carrying wire, its strength decreasing as the distance from the wire surface increases.

10) The article deals with metals, most of them being excellent conductors.

11) Many technical and scientific problems having been solved, the first spaceflight could be realized.

12) The circuit being broken, the magnetic field disappears.

13) Transistors are very sensitive to light, some of them reacting even to starlight.

14) The first man-made satellite having been sent up, it became possible to investigate various types of radiation.

15) The resistance being very large, in current in the circuit was small.

16) A great variety of substances are semiconductors, germanium and silicon being the most important of them.

17) A series of attempts having been made, Lodygin came to a successful solution of the problem.

18) Atoms consist of three parts of particles - electrons, protons and neutrons, the number of particles determining the kind of element.

19) Electrons leaving the surface, the metal become positively charged.

20) A new radio set having been shown to them, they began to examine its details.