2. Say if the following sentences are true or false.

1. Metals commonly didn’t use to make conductors include copper and aluminum. 2. Interference occurs when a conductor picks up stray electricity from other conductors or from the air. 3. Simple cables aren’t made up of a single pair of insulated wires twisted together. 4. Communication cables are laid underground and along the ocean floor, or they are mounted on poles. 5. Most cables aren’t designed to carry more than one message at a time.

3. Insert missing words, use the text’s vocabulary:

1. Most communications cables consist of … (metal wires that carry electric current) and insulation. 2. Insulation is made from such … materials as plastic and paper pulp. 3. Burying cable protects it from … weather and keeps the land aboveground uncluttered. 4. These underwater cables need tough outer coverings so that they can … strong ocean currents. 5. Electronic … at each end of the cable sort out the various conversations.

4. Translate these sentences into your native language:

1. Insulation holds the electricity in the conductors and protects the conductors from damage. 2. Insulation is made from such multiconductor materials as plastic and paper pulp. 3. In many cases, multiconductor cables are enclosed in a heavy sheath made up of several layers of aluminum or plastic. 4. Communication cables are laid underground and along the ocean floor, or they are mounted on poles. 5. Engineers have developed two kinds of cables that can carry especially large quantities of messages at once.

5. Retell the text.

Text 9

Coaxial cables

Words and word combinations:

Coaxial cables – коаксиальный кабель

flexible metal tube – гибкая металлическая трубка

rigid – негнущийся, негибкий

axis – ось

outer conductor – внешний проводник

repeaters – трансляционный усилитель

amplifiers – усилители

electronic devices – электронные приборы

transistors – транзистор

long-distance calls – междугородний, международный звонок

variety of special features – разнообразные специальные свойства

communications medium – средства связи

Coaxial cables (also called shielded cable) are made up of two conductors. The outer conductor is a rigid or flexible metal tube, and the inner conductor is a wire running through its center. Insulation holds the wire in place. The tube and the wire have the same axis (center) and are therefore called coaxial. A typical coaxial cable has about the same diameter as a pencil, and as many as 22 cables may be bundled together to make a larger cable.

A coaxial cable’s outer conductor shields the electric signals it carries from outside inter-ference and helps pre-vent the signals from escaping. In addition, special amplifiers called repeaters are insulated at various points along many coaxial cable systems to strengthen the signals. These amplifiers help prevent cable loss. Cable loss is the gradual weakening of signals as they travel along the cable. Repeaters consist of such electronic devices as transistors.

Many telephone calls, especially long-distance calls, travel over coaxial cables. When used for telephone conversations, coaxial work in pairs. One coaxial carries signals in one direction, while the other handles signals from the other direction. A pair of coaxial may handle as many as 13,200 telephone conversations at once.

Cable television systems use coaxial cables to transmit TV programs. A single cable can carry as many as 100 television signals at once. As a result, cable TV systems can transmit regular network programs as well as a variety of special features. Coaxial cables are most often used as the primary communications medium for locally connected networks in which all computer communication is within a limited geographic area, such as in the same building.