II. Learn the following words. Current струм ; direct ~постійний струм ; alternative ~змінний струм

Current струм; direct ~постійний струм; alternative ~змінний струм

Needle стрілка (приладу)

Insulator ізолятор, ізоляційний матеріал

Leak away просочуватися

Gummy клейкий

III. Find the English equivalents for the following Ukrainian words and word combinations:

a) йти по проводу; поєднувати за допомогою проводу; зі швидкістю світла; провід, що проводить струм; відправляти повідомлення; в усьому світі; винахідник; передавати; З. великою швидкістю; сухе повітря- гарний ізолятор;

b) to connect by a wire; to send messages; at great speed; all over the world; with the speed of light; to flow along a wire; to transmit; a wire carrying a cur­rent; to invent; dry air is a good insulator.

VI. Read and translate the text: “MESSAGES BY ELECTRICITY”

Electricity completely changed communications. Once it was discovered that an electric current would flow along a wire, it seemed possible that it could be used for messages. As long as two places were connected by a wire electric cur­rents could be sent along it. They could be sent with the speed of light. The question was how could electric current make words?

Real telegraphs were not possible until it was proved that electricity and magnetism were connected. It was found that a needle of a compass moved when it was put near a wire with a current flowing through it. A compass needle is a magnet. If a wire carrying a current could move it, then the wire must be a magnet too.

A lot of people began to see how electro-magnets could be used to send messages. One of the most famous people of all in communication is Samuel Morse. He invented the Morse code. This code is still used in signaling all over the world. His idea was simple. He thought of using time, sending cur­rent along a wire for a long time or a short time. Combining, different sets of these " impulses", just using the long or short, he made a code for the whole alphabet, and the numbers from; 0 to 9.The Morse code simplified sending messages. It was also very fast. With practice, the Morse code can be read at 30 words a minute or more. It became the most widely used code because it was the easiest to understand and the fastest to transmit. The telegraph meant that at last people could send messages a long way at great speed. Soon people wanted to send messages even farther.

If two places on land, say, London and Manchester could be connected by wire, why could not the lands themselves — England and America, for instance, be connected by wires under the sea? This was a question quickly answered after the telegraph was proved to work. There were some problems about this, however. The main one was insulation, which means protecting the wire so that electric current does not leak away. Dry air is a good insulator, but sea water is not. If a wire was laid under water, the current would all leak away, In any case, all the insulating substances known up to then could be damaged by sea water. But in 1847 gutta-percha was introduced as an insulating material. Gutta-percha is a gummy substance obtained from trees, like rubber, and it does not allow electricity to flow through it easily.

After several unsuccessful attempts, in 1866 Britain and America were linked by the underwater cable by the famous cable-laying ship the Great Eastern. After that cables were laid all over the world, and nowadays it is possible to tele­graph from almost everywhere.