Вопрос № 223255 - Английский язык

Прочитайте текст и определите, какой из заголовков соответствует тексту
Current is a flow of electricity through a circuit. Let us consider two main types of current: direct and alternating. A direct current (d.c.) flows through a conducting circuit in one direction only. It flows provided a direct voltage source is applied to the circuit.
An alternating current (a.c.) is a current that changes its direction of flow through a circuit. It flows provided an alternating voltage source is applied to the circuit. Alternating current flows in cycles. The number of cycles per second is called the frequency of the current. In a 60-cycle alternating current circuit the current flows in one direction 60 times and in the other direction 60 times per second.

Прочитайте текст и выберите утверждение, соответствующее содержанию текста
Electricity complete changed communications. Once it was discovered that аn 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?

Прочитайте текст и выберите утверждение, соответствующее содержанию текста
Through the years other machines were invented, both to receive and transmit messages. These machines are called teleprinters. They use a code called the International 5-unit teleprinter code instead of the Morse code. It is called a "5-unit" code because a letter or a figure is made up of five impulses of electrical current, either positive or negative - three positive, two negative; one positive, four negative; and so on. All the letters are the same length in time. This is quite different from the Morse code, where E is the shortest and "nought" the longest.

Прочитайте текст и выберите утверждение, соответствующее содержанию текста
A teleprinter is really a machine which sends a typewriter message over a telegraph circuit. In fact, it looks like a typewriter and has the same keyboard. Every time one of the keys on the keyboard is pressed it sends the five impulses that make one letter or figure. It also sends a "start" impulse. This sets the teleprinter (or any number of them that are connected) at a receiving station ready to print the letter that follows immediately. A "stop" impulse brings all the teleprinters to rest after each letter or figure.

Прочитайте текст и выберите утверждение, соответствующее содержанию текста
In the early days of the telegraph and the telephone, men observed that signals sometimes jumped across the space between wires running next to each other, so that messages sent to one person went to another. They realized that electricity could pass through the air as well as along a wire. Just as sound travels through the air in waves, so electricity travels through the air in what we call radio waves. A. S. Popov, a Russian inventor, had the idea of sending messages by radio waves, or "by wireless". He constructed a coherer detector for the study of lightning discharges and his receiver was described in 1895.

Прочитайте текст и выберите утверждение, соответствующее содержанию текста
Radio was invented in Russia. The world's first receiver was constructed in 1895 by the great Russian scientist Alexander Popov. There were no transmitters then, therefore his receiver could only pick up signals produced by lightning discharges during a thunderstorm. A. Popov demonstrated a device called a "storm indicator" at a meeting of the Russian Physico-Chemical Society in St. Petersburg on May 7, 1895. This day is marked now as Radio Day. Soon Alexander Popov found a way of transmitting Morse code signals. In 1897 he sent the world's first wireless telegram over a distance of 600 m and four years later the range of transmission was increased to 150 km. Nowadays radio communication has no limits.