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V. Form sentences combining suitable parts of the sentences given in columns I and II.
| I | II |
| 1. The generator | measures the temperature of hot melted metals. |
| 2. The lightning conductor | lifts objects weighing thousands of tons |
| 3. the motor | turns electrical energy into mechanical energy |
| 4. the electric crane | protects buildings from lightning strokes |
| 5 The pyrometer | converts mechanical energy into electrical energy |
VI. Answer the following questions:
1. What is a motor?
2. What machine reconverts electrical energy into mechanical energy?
3. Where are motors used?
4. In what household appliances are the motors used?
5. How are the motors classified?
6. What are the most common motors?
Supplementary reading
VII. Look at the plan of a simple two-pole DC electric motor.Try to explain the function of each component.
Inside an Electric Motor
The motor has six parts, as shown in the diagram below:
· Armature or rotor
· Commutator
· Brushes
· Axle
· Field magnet
· DC power supply of some sort
Parts of an electric motor
An electric motor is all about magnets and magnetism: A motor uses magnets to create motion. We know about the fundamental law of all magnets: Opposites attract and likes repel. So if you have two bar magnets with their ends marked "north" and "south," then the north end of one magnet will attract the south end of the other.
On the other hand, the north end of one magnet will repel the north end of the other (and similarly, south will repel south). Inside an electric motor, these attracting and repelling forces create rotational motion.
In the above diagram, you can see two magnets in the motor: The armature (or rotor) is an electromagnet, while the field magnet is a permanent magnet (the field magnet could be an electromagnet as well, but in most small motors it isn't in order to save power).
Heating system
Reading
I. Read the following words:
water panel, water tank, through, shower head.
II. Which way does the water flow in this system? Draw arroys to show the direction of the flow.
The main parts of this system are water pipes, a solar water panel, a water tank, an inlet, a valve and a shower head. The tank is above the solar panel.
Cold water enters the system the inlet. It then flows into the tank. From here, the water flows into the solar panel.
The Sun heats the water in the panel. The hot water rises and flows from the panel into the tank. In the tank, hot water stays at the top and cold water sinks to the bottom.
When you open the valve, hot water flows from the tank, through the valve, to the shower head. Here it finally leaves the system.
Vocabulary
III. Remember these words:
| pipe, tank, inlet, valve, to sink, to flow, to sink. |
Date: 2015-12-11; view: 3174