Lesson-34Text: ELECTRON TUBES Let us consider electron tubes. Electron tubes in use nowadays are a diode, a triode, a tetrode and a pentode. The main parts of electron tubes are electrodes. Electrodes are placed into a glass or metal bulb. A diode contains the cathode and the plate. When a diode operates the cathode emits electrons, the plate collects. A triode contains the cathode, the plate and the control grid. When the tube operates the cathode emits electrons, the plate collects them and the grid controls the flow of electrons. There-fore, the grid is called a control grid. A tetrode contains the cathode, the plate, the control grid and the screen grid. When a tube operates it may oscillate. The function of the screen grid is to eliminate oscillations. There-fore it is called a screen grid. A pentode contains two electrodes and three grids: the control grid, the screen grid and the suppressor grid. When a pentode operates the suppressor grid eliminates the secondary emission. Common troubles in tubes are an open heater and low emission. These troubles result from constant use or from some other reason. In case a tube has a trouble it stops operating or operates badly. A tube with a trouble should be replaced by another one.
EXERCISES A Find the correct variant. Remember it: A pentode contains a) the cathode, the plate, two screen grids and the suppressor grid b) the cathode, the plate, the control grids, the screen grid and the suppressor grid Tetrode contains c) the cathode, the plate, the suppressor grid and the screen grid d) the cathode, the plate, the suppressor grid and control grid
Answer the questions: 1.What electron tubes are in use? 2.What are the main parts of electron tubes? 3.What does a diode contain? 4. What does a triode contain 5.What does a tetrode contain? 6. What electrodes contain a pentode? 7.What common troubles in tubes? Test .1. The main parts of electron tubes are_________
a}batteries b}electrodes c}wires d}plates
2_____ contains the cathode and the plate. a}a pentode b}tetrode c}triode d}diode
3. _____ contains the cathode, the plate and the control grid.
a}a pentode b}tetrode c}triode d}diode 4._____contains the cathode, the plate, the control grid and the screen grid.
a}a pentode b}tetrode c}triode d}diode
5. _______ contains two electrodes and three grids: the control grid, the screen grid and the suppressor grid.
a}a pentode b}tetrode c}triode d}diode
Glossary
SIW Find and learn 10-12 words, write examples
SIWT Retelling the text
Literature:1. Orlovskaya I.V.”English”-Moskow-2007 2. Raymond Murphy”Essential Grammar in Use”
Lesson-35 VOCABULARY phrasal verbs
Match the question 1-7 with the pictures A-G
1 What time do you wake up in the morning? 2 Do you use an alarm clock to wake up? 3 Do you turn off the alarm clock to wake up? 4 What's the first thing you turn on after you wake up? 5 Do you get up immediately after you wake up? 6 How do you fell when you first get up? 7 When you fell when you first get up?
GRAMMAR word order of phrasal verbs
b) Complete the rules about separable phrasal verbs in each sentence. 1 If the object of a phrasal verb is a ______, you can put it after the verb + up, on, etc. OR between the verb and up, on, etc. 2 If the object of a phrasal verb is a ______, you must put it between the verb and up, on, etc. D) Match the sentences. Then cover the sentences on the right. Try to remember them. 1 Your mobile's ringing. [ ] A A You need to give it up. 2 This is an important rule. [ ] B Put them away. 3 I can't hear the music. [ ] C Turn it up. 4 If you don't know what the words mean. [ ] D Throw it away. 5 This is an immigration form. [ ] E 6 Coffee is bad for you. [ ] F Please fill it in. 7 Your clothes are on the floor. [ ] G Write it down. 8 That's rubbish. [ ] H look them up.
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READING Do you know what these scientific words and expressions mean? _______________________________________ a gene DNA your 'body clock' research_
Read the a article about morning and evening people. Choose a, b,or c. Scientists say that if we are bad at getting up
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