Text 3. Types of electric circuitsElectrons with a negative charge, can’t ‘jump’ through the air to a positively charged atom. They have to wait until there is a link or bridge between the negative area and the positive area. We usually call this bridge a ‘circuit’. When a bridge is created, the electrons begin moving quickly. Depending on the resistance of the material making up the bridge, they try to get across as fast as they can. If you are not careful, too many electrons can go across at one time and destroy the ‘bridge’ or the circuit, in the process. We learned about electrons and the attraction between positive and negative charges. We also learned that we can create a bridge called a ‘circuit’ between the charges. We can limit the number of electrons crossing over the circuit. So, we can make electricity do something for us while they pass their way. For example, we can ‘make’ the electrons ‘heat’ a filament in a bulb, causing glow and give off light. When we limit the number of electrons that can cross over our circuit, we say we are giving it ‘resistance’. We ‘resist’ letting all the electrons through. Copper wire is just one type of bridge we use in circuits. Before electrons can move far, however, they can collide with one of the atoms along the way. This slows them down or even reverses their direction. As a result, they lose energy to the atoms. This energy appears as heat, and the scattering is a resistance to the current. Current refers to the movement of charges. In an electrical circuit electrons move from the negative pole to the positive. If you connect the positive pole of an electrical source to the negative pole, you create a circuit. These charges change into electrical energy when they are connected in a circuit – similar to connecting the two poles on opposite ends of a bulb. Along the circuit you can have a light bulb and an on-off switch. The light bulb changes electrical energy into light and heat energy. When you press the switch the circuit is ‘closed’ and the current flows turning your light bulb on. When your switch is up, the circuit is ‘open’ and current can not flow turning your light bulb off. The number of electrons we are willing to let across the circuit at one time is called ‘current’. We measure current using amperes or ‘Amps’. One AMP is defined as 6.25x1018 electrons moving across your circuit every second. Since no one wants to remember such a big number, that big number is called a ‘coulomb’ after the scientist Charles A Coulomb. The amount of charge between the sides of the circuit is called ‘voltage’. We measure it in Volts. The word “volt” was named after another scientist, Alexader Volta, who built the first battery. One volt is defined as the amount of electrical charge needed to make one coulomb. Joule is also named after a scientist, James Prescott Joule. Voltage, Current and Resistance are very important to circuit. If either voltage or[1] current is too big you could break the circuit. But if either voltage or current is too small, the circuit will not be able to be useful to us. In the same way, if the resistance is too big none of the electrons would be able to get through at all, but if it were too small, they would rush breaking the circuit. When we have only one circuit that electrons can go through to get to the other side we call it a ‘series circuit’. If we were to set up another circuit next to the first one, we would have two circuits between the charges. We call these ‘parallel circuits’ because they run parallel to each other. You can have as many parallel circuits as you want. Parallel circuits share the same voltage, but they allow more paths for the electricity to go over. This means that the total number of electrons that can get across (the current) can increase, without breaking either circuit. An electric motor uses circuits wound round and round. These wound circuits are suspended between magnets. A motor works through electromagnetism. It has a coiled up wire (the circuit) that sits between the north and south poles of a magnet. When current flows through the coiled circuit, a magnetic field is produced. The north pole of the fixed magnet attracts the south pole of a coiled wire. The two north poles push away, or repulse each other. The motor is set up in the way that attraction and repulsion spins the centre section with the coiled wire.
Exercise 26. Answer the following questions. 1. What is called a ‘circuit’? 2. What does the movement of electrons depend on? 3. How does resistance influence electrons? 4. How is a circuit created? 5. When does a charge change into electrical energy? 6. When is circuit ‘closed’ or ‘open’? 7. What is called ‘current’? 8. What unit is used to measure the number of electrons moving across the circuit every second? 9. How can we measure the amount of charge between the sides of the circuit? 10. Why are voltage, current and resistance very important to circuits? 11. What circuit is called a ‘series circuit’? 12. How are parallel circuits arranged? 13. How does the electric current flow in a parallel circuit? 14. What prevents parallel circuit from being broken? 15. What phenomenon is used in a motor operation? 16. How is a magnetic field produced? 17. How does the magnetic field act? Exercise 27. Translate the following universal words without a dictionary. Atom, electron, limit, ampere, volt, coulomb, battery, joule, parallel, electricity, motor, electromagnetism, magnet, magnetic.
Exercise 28. Translate into English, give the corresponding nouns; make up possible word combinations in English. Рухатись, опиратись, притягувати, відштовхувати, зіштовхуватись, направляти, вимірювати.
Exercise 29. These words are used both as verbs and as nouns. Translate and remember them. To limit – limit; to use – use; to switch – switch; to wind – wind; to result – result; to charge – charge; to name – name; to rush – rush; to share – share; to heat – heat; to cause – cause.
Exercise 30. Translate and comment upon the following grammar forms. Can limit; could break; was named, would rush; will not be able to be; to be useful; would be able to get; is defined; were to set up; can go through to get; is produced; attracts; is set up; causing.
Exercise 31. Use the verbs in brackets in the correct tense and voice form. Translate the sentences. 1. We (limit) the number of electrons crossing over the circuit. 2. We can ‘make’ the electrons (heat) a filament in a bulb, (cause) glow and give off light. 3. Current (refer) to the movement of charges. 4. We measure current (use) amperes. 5. The amount of charge between the sides of the circuit (call) ‘voltage’. 6. The word volt (name) after Alexader Volta, who (build) the first battery. 7. If either voltage or current is too small, the circuit will not (can) to be useful to us. 8. A motor (work) through electromagnetism. 9. When current (flow) through the coiled circuit, a magnetic field (produce). 10. The motor (set) up in the way that attraction and repulsion (spin) the center section with the coiled wire.
Exercise 32. Match the English-Ukrainian equivalents.
Exercise 33. Give Ukrainian equivalents. Heat energy; electrical source; opposite ends; charged atom; negative area; positive area; electrical energy; on-off switch; light bulb; sides of the circuit; electric charge; series circuit; parallel circuit; wound circuit; coiled circuit; magnetic field; coiled wire; north poles.
Exercise 34. Complete the sentences. 1. Electrons with a negative charge, can’t ‘jump’ through the air to a positively _____. 2. Too many electrons can go across at one time and destroy the _____. 3. _____ refers to the movement of charges. 4. If you connect the _____ of an electrical source to the _____, you create a circuit. 5. Along the circuit you can have a ______ and an _____. 6. The light bulb changes _____ into light and _____. 7. _____ are very important to circuits. 8. ____ share the same voltage. 9. A motor works through _____. 10. When current flows through the coiled circuit, a ____ is produced.
Exercise 35. Match each of the following definitions with the correct terms.
Exercise 36. Translate into English. 1. Коло або схема – це місток між позитивно та негативно зарядженими площинами. 2. Коли ми обмежуємо кількість електронів, що проходять у колі, ми створюємо опір. 3. В електричному колі електрони рухаються від негативного до позитивного полюсу. 4. Якщо з’єднати позитивний полюс джерела живлення із негативним полюсом, утворимо схему. 5. Кількість електронів, що проходить у колі за певний проміжок часу, називають струмом. 6. Сила струму вимірюється за допомогою амперметра. 7. Один ампер становить 6,25х1018 електронів, що проходить по колу кожної секунди. 8. Кількість зарядів між полями кола називається напругою. 9. Напруга вимірюється у вольтах. 10. Схеми, що з’єднуються паралельно, називаються паралельними схемами.
Exercise 37. Learn the following words and word combinations. Metrology – метрологія measurement – вимірювання metric – метрика; метричний scale – шкала quantity – величина; кількість phenomenon (pl. phenomena) – явище existence – існування reference – давати посилання (на джерело) estimation – оцінка determination – визначення extent – ступінь, міра dimension – розмір capacity – ємкість magnitude – величина set – набір, ряд integer – ціле число ratio – відношення, коефіцієнт, співвідношення product – результат, добуток count – злічувальне число engineering – техніка, конструювання uncertainty – невизначеність designate – визначати, встановлювати derive – походити substitution – заміщення stride – відстань між широко поставленими ногами multiple – кратне число submultiple –дільник substance – речовина intensity – сила; енергія; інтенсивність weighing scale – терези commerce – торгівля
Exercise 38. Read the given text1 and make the plan of key ideas.
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