5. What do you think:

1. Who inspired Orville and Wilbur Wright to invent an airplane?

2. What technical problems were solved by the brothers?

3. When was the first plane ready to be tested?

4. What was the name of the plane?

5. Why were the brothers sure that the plane would be able of lifting and maintaining itself in the air?

V. Discuss with your groupmates:

1. What new information about the first airplane have you learnt from the text?

2. Read the statement by Orville Wright in the text and say if you agree or disagree with him?

Radio

I. First thoughts

How do you think a radio operates? Do you know anyone who likes to make different electrical goods such as radios, computers, etc.?

II. Study these words. Make sure you know them.

transmitter, electromagnetic, broadcast, equipment, frequency, message.

III. Read the text and do the tasks following it:

Do you have a favorite radio station? What do you like about it? Have you ever wondered how your radio is able to produce the sounds and the music that you like to hear?

Radio programs are sent by a machine called a transmitter to your radio which is called a receiver. The programs don't travel through wires like telephone messages do. They are sent through the air over long distances by electromagnetic waves. These waves are called radio waves and were discovered by a German scientist named Heinrich Hertz. He discovered that these waves could carry sound signals. He also discovered that radio waves have different lengths.

Guglielmo Marconi, an Italian, invented a microphone that changed sound waves into electronic signals, and then he developed a receiver that turned them back into sound again. He also found a way to keep waves of the same length together and keep those of different wave lengths separate. On his equipment, a radio wave looked like a letter "s" lying on its side. Short waves curved up and down more times each second than longer ones, so he divided all the waves by how many times they curved each second or by how frequently they curved. He called each group a frequency. The numbers on your radio dial are different frequencies. Different stations can broadcast their programs at the same time using different frequencies.

Later, scientists found that by using only the top half of a radio wave they could reduce static and other noise that interfered with clear sound. This kind of radio transmission is called FM broadcasting because the frequency has been modulated or changed.

IV. Comprehension Check.

1. Match the words with their meanings placing a proper letter on each blank.

_1. microphone a. an apparatus which changes radio waves into sounds

_2. to invent b. the metal in the form of thread

_3. receiver c. having a magnetic force produced by an electric current

_4. curse d. an instrument that receives sounds and changes sounds

into electrical energy

_5. to discover e. to find something for the first time

_6. electromagnetic f. to make or produce something for the first time

_7. wire g. a line of which no part is straight and which contains no angles