PHYSICS Help!!!?

Question

1. One advantages of optical fibres over ordinary cables of the same thickness is?

a) They are made of glass.
b) They can carry more information.
c) Their signals weaken more over long distances.

2. How do signals travel through optical fibres?

a) As microwaves
b) As radio waves
c) As infrared radiation

3. A signal that varies continuously in frequency is called?

a) A digital signal
b) An analogue signal
c) An AM signal

4) How many different states are there in a digital signal?

a) One
b) Two
c) Three

5. Which type of signal maintains its quality the best?

a) Digital signals
b) Analogue signals
c) Both types are the same

Do as much as you know and if you could EXPLAIN in that will really help Cheers!

Answer 1

1) A
2) C
3) C
4) B
5) A

Answer 2

Optical fibers are capable of carrying more information than their copper counterparts. This is due to the carrier frequency being higher, which means more bandwidth. The greater the bandwidth, the more information can be carried because the signal can "wiggle" faster. The infrared light in fiber optical cable is in the Tera-Hertz range(trillions of cycles/second) while copper cables are limited to the Giga-Hertz range(billions of cycles/second). This answers questions 1 and 2.
Digital signals are normally limited to 2 discrete states, on and off. This is easy for a circuit to make and easy for a circuit to recognize on the receiving end. It is done this way to avoid the signal degradation than normally happens in analog signal transmission. As the signal goes through the wire, it looses voltage and picks up noise from outside. The more wire the signal has to go through the greater this effect. This same thing happens to a digital signal. But as long as the signal is still big enough to be properly interpreted as a on or an off nothing is lost, because we don't care about the exact shape of the signal anymore, only if it was on or off.

I think the correct answer to number three is an FM(frequency modulated) signal. But I don't see that answer listed.

Answer 3

1. B, process of elimination, fiber optics can bend, so it's hard for me to see it as glass. The question asked for an advantage, so a weaker signal over long distance isn't the answer, so it has to be B.

2. C, I know fiber optics use light that bounces around the tube to convey information.

i have no idea bout the rest. sorry man.
3. ?
4. ?
5. ?

Answer 4

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