XII. State whether the following statements are true or false. Use only evidence from text.

1. Vacuum tubes are smaller than transistors and consume less power.

2. The emitter usually has a negative electric charge and the collector usually has a positive charge.

3. Electric current outside the tube flows through the collector and heats it.

4. The grid consists of a wire mesh located between the emitter and the collector.

c. The current of electrons flows from the emitter to the collector.

XIII. Match the words and word-combinations from text 15a with their corresponding definitions:

1. vacuum tube a. an electron tube evacuated to a sufficiently low pressure that its electrical characteristics are independent of any residual gas

2. integrated circuit b. a two-electrode tube

3. transistor c. vacuum tubes filled with low-pressure gas

4. diode d. a semiconductor device with at least three terminals, used in circuit as an amplifier, detector, or switch

5. electrode e. a solid electric conductor through which an electric current enters or leaves an electrolytic cell or other medium

XIV. Translate the following two-component and multi-component terms into Ukrainian:

multielectrode tube, cathode-ray tube, microwave tube, gas-filled tube, semiconductor triode, hard tube, soft tube, thermal emission, discrete device, integrated circuit.

XV. Make up a plan of text 15A.

XVI. Annotate text 15A.

XVII.Retell text 15A.

TEXT 15(B)

NOTES

1. audio amplification посилення звукових частот

2. widespread широко поширений

3. high-fidelity sound reproduction високоякісне відтворення звуку

4. aesthetic естетичний

TEXT 15(B)

What are the most important applications of vacuum tubes

Vacuum tubes were essential to the development of the science and technology of electronics. From the 1920’s to the 1950’s, all electronic equipment used vacuum tubes. Since that time, the vacuum tube has been replaced in most kinds of electronic equipment by a newer device called the transistor. Transistors do the same jobs as vacuum tubes. But they are smaller and more reliable and consume less power. Certain electronic equipment still uses various types of vacuum tubes. For example, the screen of a television set is one end of a large vacuum tube called a cathode-ray tube.

Vacuum tubes were critical to the development of electronics technology, which drove the expansion and commercialization of radio broadcasting, television, radar,high-fidelity sound reproduction, large telephone networks, modern types of digital computer, and indastrial process control. Some of these applications pre-dated electronics , but it was electronics that made them widespread and practical.

For most purposes, the vacuum tube has been replaced by solid-state semiconductor devices such as transistors and solid-state diodes: for most applications, they are smaller, more efficient, more reliable, and cheaper. However, tubes are still used in specialized applications: for engineering reasons, as in high-power radio frequency transmitters; or for their aesthetic appeal, as in modern audio amplification. The cathode-ray tube forms the basis of a device called an oscilloscope. Oscilloscopes have many uses in scientific laboratories, hospitals, computers, and automobile repair shops. Cayhode ray tubes are still used as display devices in television sets, video monitors. For example, the screen of a television set is one end of a large vacuum tube called a cathode-ray tube. Vacuum tubes still have some applications as high power pulse switches, high end audio and guitar amplifiers, some high power R. F. applications. A specialized form of the electron tube, the magnetron, is the source of microwave energy in microwave ovens and some radar systems. Radar systems use oscilloscopes to change radar signals into visible light patterns.