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Pronunciation Drill 1

Practise [s, z, iz] sounds at the end of the words:

1. [s] exists, emits, accelerates, deflects, makes, limits

parts, groups, plates, volts, types

2. [z ] gives, means, speeds, is, has, does, provides, removes,

performs, extends, falls

tubes, screens, ones, anodes, walls, fields, potentials

3. [iz] uses, discusses, produces, diverges, focuses, ceases

surfaces, inches, images, places

Pronunciation Drill 2

While reading these words pay attention to the stress markings;

`focus `cylinder im`pinge

final accurate increase (v)

increase (n) several deflect

hundred multiple effect

TEXT 9

CATHODE-RAY TUBE

1. Now let us turn to cathode-ray tubes (abbreviated C RT) that provide, a visual representation of voltage and

current waveforms. Cathode-ray tubes consist of three basic components: 1. the electron gun, 2. a deflection system, 3. a fluorescent screen. These essential parts of a cathode-ray tube are mounted inside a highly evacuated, funnel-shaped glass envelope (as shown in Fig. 6) the large end of

which has the fluorescent screen coated upon the inside

surface.

2; The electron gun has the job of producing and focu­sing the electrons into a narrow beam so that it makes a tiny spot, when impinging on the fluorescent screen. A broad beam is of little use for accurate display of waveforms or TV pictures. An electron gun of the electrostatic type con­sists of an indirectly heated cathode, a control grid, an ac­celerating electrode or grid, a focusing anode, and a final accelerating anode. These electrodes are in the form of cy­linders surrounding the cathode. Connections to the electro­des are brought to pins in the base.¹

3. The cathode emits the electrons, the control grid determines the amount of electron flow by means of the negative bias placed on it, and the accelerating electrode being highly positive with respect to the cathode speeds up the electrons passing through it. Electrons passing through the openings in the accelerating electrode are focused into a sharp electron beam by the combined effect of the focu­sing anode and the final accelerating anode, which are in effect a multiple electronic lens system.² Both the accele­rating and focusing anodes are at a positive potential with respect to the cathode but the voltage on the focusing anode is always considerably lower by several hundred to thous­and volts than that on the final accelerating anode.

(to be continued)

Commentary

1. are brought to pins in the base — выведены на штырь­
ки в основании лампы

2. are in effect a multiple electronic lens system — явля­
ются фактически составной системой электронных линз

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