| << | < | 139 | 140 | 141 | 142 | 143 | 144 | 145 | 146 | 147 | 148 | > | >> |
2/ Do you hove your favourite radio station? Have you ever wondered how it works?
Radio programmes are sent through the air over long distances by electromagnetic waves. They are called radio waves. A German scientist Heinrich Hertz discovered the radio waves and he also discovered that they have different lengths.
3/ Have you ever wondered how your voice can travel through the telephone?
Alexander Graham Bell, who invented the first telephone, discovered that voices could travel with the help of electricity.
When you speak into the telephone you make a thin piece of metal vibrate. The electric current makes a copy of your voice. And that's how your voice travels through the telephone.
4/ Work in groups. Discuss the following questions and present your ideas.
1. What are the advantages of the Walkman? Make a list.
2. What are the disadvantages of the Walkman? Make a list.
3. What do the people use robots for?
What are their advantages and disadvantages?
4. How often do you listen to the radio? What are your favourite radio programmes?
5. What are the advantages of the telephone?
6. What other models of communication do you know?
