1. ## Question

Does anyone know the answer to this ? (how to work it out would be very very useful, thanks)

Given that the speed of an electrical signal in a piece of cable is
2 * 10 8 metres/sec, how long does it take for a signal to get from one end of a 750 metre Ethernet to the other?

1 ) 15 microsec
2 ) 37.5 microsec
3 ) 3.75 millisec
4 ) 1.5 microsec
5 ) 3.75 microsec

2. I think many here could answer that but I don't think helping someone with their homework is right.
Well, it's not wrong.. but it's the principle of it all.. you're supposed to use your brain.
Sure you have the internet to help you learn.. searching and discovering is one thing but asking us outright to do it, is entirely another. Good luck when it comes time for the test.. hehehe

3. Thanks for pointing that out ... i realise now that i rushed into asking for the answer when i should have really spent a little more time working it out myself ...

4. Not a big deal mike.. You're not the first to try to get something for nothing.. &lt;grin&gt;

Now, why don't you put out what you think it is with your proof.. then you'll get a response.

And when I find out who gave me +'s for my post.. watch out.. my negs are coming.. hehehe

Open season for those (with 5 green gifs or less, plz) to balance and even that post out.

5. ok i've look at it for longer and i don't seem to be getting any closer, i have the exam soon and i just want to know how to work it out, i don't really mind about the answer, it's more the method to work it out i'm looking for... any help would be greatly accepted

6. mikester2,

I never was much good at math(S)

You have: Distance to travel in metres / speed in metres per second which I would guess to be

750 / 200,000,000 which is 0.00000375 seconds, which I suppose are 3.75 microseconds?

Given that the speed of light is 299,792,458 metres per second, this implies some resistance/impedance in the cable, which sort of makes sense?

What you do is convert all the measurements to common denominators and the answer "drops out"? In this case we have metres and seconds for distance and time?

You are lucky I do not teach you: I would have asked the "speed of light in furlongs per fortnight" ..............

the speed of light = 1.8026175 × 10 to the 12 furlongs per fortnight

Just type the bit between the inverted commas into google and hit search..........it has a calculator.

Cheers

7. Thank you very much

8. Hi Mike,

Nice of you to respond.....do try the google thing. You can even work out the volume of the planet Jupiter in imperial teaspoons

My cousin is professor of physics at one of you universities..........he sends me that kind of stuff

Cheers

9. I thought the same thing... this has to be someones homework...

10. OK, no names, no pack drill..

There were times at school, and those are very vague memories

When I "did not get on with a teacher".......personality conflicts IMHO should not be allowed to disrupt your education?

The gentleman twice indicated that he needed to know the principles, so I told him............

I am old, and had old fashioned teachers.........when I told my one that if I failed it would be his fault..........he helped me out

The exam was external, and I was one of the few who got an "A"

He was amazed by that...........later in life I look back and think that it is just like a PC....a screwdriver (Tool) and a couple of hours if you know what you are doing?

sorry for being a boring old fart

Cheers

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