Data Sheet
-94-
188. Fiber Optic Communication Underwater
Build the circuit shown on the left and turn on the switch (62). Press the
press switch (61) and you will see the bi-directional LED (71) and colorful
LED (72) light. Release the press switch (61) and the bi-directional LED
(71) and colorful LED (72) will stay bright briey and then turn dim. One of
the benets of ber optic transmission is that bers can be placed under
water. In fact, submarine communication cables (underwater cables)
primarily use ber and carry about 99% of data exchanged internationally.
189. Fiber Optic Communication – Near the Speed of Light
Replace the 1kW resistor (42) in project #188 with the 5.1kW resistor (43) and
then turn on the switch (62). Press the press switch (61) and you will see the
bi-directional LED (71) and colorful LED (72) light. Release the press switch (61)
and the bi-directional LED (71) and colorful LED (72) will stay bright for a little
while and then turn dim. Light travels at a speed of approximately 300 million
meters/second. Since bers use light to communicate, ber transmissions are
nearly as fast as the speed of light (about 99.7% of the speed of light). Actual
data speeds are related to various modulation, coding and decoding techniques,
but one thing is for sure…the time it takes for the data transmission to travel
over the ber is not a limiting factor in the data speeds.
190. Advantages of Fiber Optics
Replace the 1kW resistor (42) in project #188 with the 10kW resistor (44)
and then turn on the switch (62). Press the press switch (61) and you will
see the bi-directional LED (71) and colorful LED (72) light. Release the press
switch (61) and the bi-directional LED (71) and colorful LED (72) will stay
bright for a while and then turn dim. Some of the advantages of ber optic
transmission are that they do not overheat and are not affected by rain,
wind and other weather factors. They are also stronger than copper and can
endure much larger tension than copper.
191. Disadvantages of Fiber Optics
Replace the 1kW resistor (42) in project #188 with the 100kW resistor (45) and
then turn on the switch (62). Press the press switch (61) and you will see the
bi-directional LED (71) and colorful LED (72) light. Release the press switch (61)
and the bi-directional LED (71) and colorful LED (72) will stay bright for a long
time before turning dim. The major disadvantage of ber optic is that it is difcult
to make connections. The core of optical cable is as ne as a human hair, so
when making splices the ber cores must be perfectly aligned. Also, the ends
of the optical ber must be highly polished to allow light to pass with little loss.
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