Английский язык: Методические указания и задания к контрольным работам для студентов специальности «Техническая эксплуатация транспортного оборудования», страница 9

Задание 4. Переведите предложения, обращая внимание на страдательный залог. (Passive Voice).

1. When the plate was connected to the negative terminal the current decreased to zero. 2. If the temperature of the body is raised the electrons leave its surface. 3. A pulsating cloud of electrons around the body is known as a space charge. 4. Secondary emission is produced when a fast-moving electron hits any material. 5. Electrons are released from the surface of a metal as the result of the energy imparted by light.

Задание №5. Переведите предложения на английский:

1. В 1883 году Эдисон исследовал причины сгорания нитей в лампах накаливания. 2.Он поместил металлическую пластину в вакуумный баллон с нитью накала и соединил ее с положительной клеммой батареи. 3.Он обнаружил протекание тока между пластиной и батареей. 4.Эффект Эдисона был результатом эмиссии электронов с нити накала. 5. Нить накала была горячей. 6.Нить накала была обнаружена облаком электронов. 7.Облако электронов вокруг горячего тела называется пространственным зарядом. 8.Если пластина положительна, она будет притягивать электроны. 9.Эти электроны будут составлять непрерывный ток в одном направлении. 10.Этот непрерывный ток имеет свойство выпрямления.

Задание №6. Ответьте на вопросы.

1.What did Edison investigate in 1883? 2. What did he place inside an evacuated bulb with a filament? 3. What did Edison discover when he connected the plate to the plate to the positive terminal of the battery? 4.Was the filament hot at that time? 5.What surrounded the hot filament? 6.Why did the plate attract electrons? 7.What kind of current across the space will these electrons constitute?

Вариант №2

Задание №1. Прочитайте и переведите письменно текст:

Cathode-Ray Tubes

A cathode-ray tube is an essential part of all oscillographs, radars, TV receivers etc. Cathode ray tubes convert an electrical signal into a visual one by shooting a beam of electrons at a fluorescent screen and deflecting the beam in accordance with the variations of the electrical signal. Cathode-ray tubes consist of an electron gun, with a focusing system, a deflection system, and a fluorescent screen, all housed in a glass envelope. The electron gun and the deflection system are mounted in the neck of the tube.

     The electron gun is usually made up of a heater-type cathode, accelerating electrode (anode), and a control grid which is inserted between the cathode and the accelerator. The cathode has the form of a cylinder enclosing the heater filament. Electron emission is obtained from the oxide coated cathode. Emitted electrons are attracted away from the cathode surface by the accelerating anode having a high positive potential (a few thousand volts) with respect to the cathode. A central hole in this anode allows the electron beam to pass along the axis of the tube. An additional electrode, known as the control grid or control electrode, is inserted between the cathode and accelerator and has a potential slightly negative (a few volts) relative to the cathode. The function of this control electrode, whose potential can be varied, is to control the electron emission rate from the cathode thus changing the brightness of the light spot on the tube screen.

     Since the electrons in the beam all have a negative charge there  will be mutual repulsion between them and as the result the beam diameter will become wider. Hence, the electron beam needs focusing. Two methods are mostly used for focusing the beam, electrostatic and magnetic focusing.

     Electrostatic focusing is accomplished by electrodes which are introduced into the tube to set up electric fields having a radial component. Inward radial forces are then exerted on the electrons passing through the region to counteract the outward space-charge force. Such an electrode system is called an electron lens. As the result, the electrons moving at some angle to the tube axis are focused into a narrow beam.