A transmission line is a pair a conducting wires held apart by an

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					University of Montenegro
Institute of Foreign Languages
                        English in Electronics and Engineering


                        Mock Test




I Read the text and choose the right answer to fill in the blanks in the
table bellow the text


A transmission line is a pair a conducting wires held apart by an insulator or
dielectric. They come in a variety of construction geometries. The simplest
and least expensive form is two-wire (ribbon) cable. Twisted pair cable
consists of two wires ___________(1) in an insulator and twisted together.
Shielded pair cable contains two wires surrounded and separated by a solid
___________(2) The dielectric is contained within a copper ___________(3)
that shields the conductors from external noise sources. The entire
construction is housed in a flexible, waterproof cover.

The use of this kind of cable is limited by two factors: attenuation and cross-
talk. When a transmission line can act as an antenna, it can also act as a
___________(4). Lines ___________(5) radiation loss are also susceptible
to ___________(6), or cross-talk. The first two types described above are
particularly prone to this fault. The shielded pair is designed to
___________(7) this pick-up.

All these lines have strong attenuation___________(8) frequencies above
1MHz. They are generally used for for low bit-rate communication. Two-wire
ribbon cable is standard for the connection of individual telephone receivers.
Twisted pair(s) is the normal method of connection for computer terminals
and short high bit-rate connections.

Attenuation increases with both frequency and ___________(9). It is usually
specified in dB/m at a particular frequency. Because of this fact, it is not
possible to give hard-and-fast rules ___________(10) the bandwidth
availability of transmission lines. A twisted pair can support rates of several
Mb/s ___________(11) short distances (metres), but over long distances
(kilometres) will be completely ___________(12) at these data-rates.
For long distances, or data-rates in excess of several Mb/s, coaxial cable is
used. Until the advent of ___________(13) fibre, coaxial lines were the
standard method of long-distance, high bit-rate communication. They are
expensive (but getting cheaper, especially as demand ___________(14)),
and only used where necessary. Typical attenuation values for coaxial cable
are 10dB/Km at 10KHz, 50dB/Km at 500MHz. For very long-haul routes,
repeaters and ___________(15) are necessary.

1. A seated            B sweetened         C sheathed      D shield

2. A electrics         B dielectric        C electrolyte   D polyethylene

3. A bread             B bride             C braid         D breed

4. A aerial            B dish              C receiver      D

5. A pick-up           B kick-up           C feed-up       D pick-off

6. A prone to          B prone at          C prone up      D prone off

7. A increase          B reduce            C reducing      D increasing

8. A on                B at                C off           D in

9. A width             B length            C height        D depth

10. A connecting       B concerning        C consisting    D collecting

11. A in               B above             C over          D up

12. A suitable         B unsuitable        C suited        D suiting

13. A optical          B twisted           C waveguide     D coax

14. A falls            B rises             C decreases     D drops

15. A electrolytes     B equalizers        C distortions   D reflections




                                      15
II Choose the appropriate verb form to fill in the blanks:

  1. In 1855 Lord Kelvin __________ (formulate) a diffusion model of the
     current in a submarine cable.
  2. When the voltage __________ (change) in a time interval comparable
     to the time it takes for the signal to travel down the wire, the length
     __________(become) important and the wire must __________(treat)
     as a transmission line.
  3. Some of the power that __________(feed) into a transmission line is
     lost because of its resistance. This effect __________(call) ohmic or
     resistive loss.
  4. The conventional telephone__________(invent) independently by
     Alexander Bell and Elisha Gray in 1876.

  5. There __________ (also, be)dramatic changes in telephone
     communication behind the scenes. Starting with the operation of TAT-8
     in 1988, the 1990s __________(see) the widespread adoption of
     systems based on optic fibres. The benefit of communicating with optic
     fibres is that they offer a drastic increase in data capacity. TAT-8 itself
     __________(be able) to carry 10 times as many telephone calls as the
     last copper cable laid at that time and today's optic fibre cables are
     able to carry 25 times as many telephone calls as TAT-8. This increase
     in data capacity is due to several factors: First, optic fibres are
     physically much smaller than competing technologies. Second, they
     __________(not suffer) from crosstalk which means several hundred
     of them can be easily bundled together in a single cable. Lastly,
     improvements in multiplexing __________(leed)to an exponential
     growth in the data capacity of a single fibre.
                                     12




III Read the text carefully and answer the questions:

Every radio transmitter emits power wirelessly. For example, the operation of
a crystal radio is powered by the radio station it is tuned to, however the
energetic efficiency is extremely low.
Small scale wireless power was demonstrated as early as 1831 by Michael
Faraday and by 1888 Heinrich Rudolf Hertz had proven that natural radio
waves exist and can be captured.

Both Nikola Tesla and Hidetsugu Yagi attempted to devise systems for large
scale wireless power transmission. Tesla claimed to have succeeded, but his
investors saw no way they could profit from it because the consumption
could not be controlled for billing and so not only refused to fund
construction of larger transmitters but had the existing ones dismantled. Yagi
also proposed a similar concept, but the engineering problems proved to be
more onerous than conventional systems. His work, however, led to the
invention of the Yagi antenna.

Another form of wireless power transmission has been studied for
transmission of power from solar power satellites to the earth. A high power
array of microwave transmitters would beam power to a rectenna. Major
engineering and economic challenges face any solar power satellite project.


1. “as early as” un the sentence “Small scale wireless power was
demonstrated as early as 1831” in line 4 means:

it should have been discovered much before __T/F___
2. Why did Tesla have problems with the
investors?_____________________________________________________
_________________________________
3. Which issues are to be dealt with solar power
systems?______________________________________________________
4. Provide at least two synonims or words with similar meanings for

   a)   to devise
   b)   to dismantle
   c)   to capture
   d)   is powered by
                                   7


Match the words with the definitions:

Generate                           A passageway or tube used for transport.


Coating                            an enveloping structure or covering
Plate                                 A fibrous or metallic group of filaments
                                      interwoven in cylindrical form to form a covering
                                      over one (1) or more wires.

Fault                                 beneath the surface of the sea

Porosity                              a sheet of metal or wood or glass or plastic

Sub-marine                            bring into existence, produce

Coaxial                               (electronics) equipment failure attributable to
                                      some defect in a circuit

Duct                                  The percentage of a soil, rock, or sediment's
                                      volume that is made up of pores.

Sheath
                               Cabling, usually comprised of a single copper cable
                               surrounded by cladding and a sheath.

Braid                   A material put over the cladding, during the drawing process, to
                        protect the fiber from the environment.

                                      5




V Correct the mistakes:


1.The amount of power that can send over a transmission line is limited.
2. Voltages have used for electric power transmission increased throughout
the 20th century.
3. Initially transmission lines were supported by porcelain pin-and-sleeve
insulators
4. Small municipal electrical utilities have not necessarily desired to reduce
the cost of each unit of electricity sold especially during the period 1880-
1890.
5. In the 19th century two-phase transmission was using.
                                       5


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posted:11/29/2011
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