Re: Simple Question



On Fri, 22 Sep 2006 04:26:20 +0100, Eeyore
<rabbitsfriendsandrelations@xxxxxxxxxxxxxxxxxxxxxx> wrote:

Chris Foster wrote:

I have a simple question. This is a qustion that I was asked in a job
interview.

If there existed and infinite two dimewnsional array of 1 ohm resisters,
what is the resistance between two point seperated by a knights move (i.e.
up two, over one, or over two and up one.......etc...)

Off the top of my head I think it's sqrt(5) ohms.

I don't think so. In terms of an exact calculation, it is (2/pi) for
an "over one, up one" move. That's exact for an infinite grid as I
understand the OP's question. The "over two, up one" has slightly
higher resistance. But not so high as to be sqrt(5). That figure is
wrong on its face. At a distance of "over two, up two" the exact
answer is (8/(3*pi)), which sets an obvious upper limit. The actual
figure for the knight's move must be between (2/pi) and (8/(3*pi)) or
else between 0.6399 and 0.8488. And that is what I found when I did
it using an entirely independent numerical method, from scratch.

Jon
.



Relevant Pages

  • Re: Photographers-Do you think outside the box?
    ... any of us really exploit those possibilities to the fullest. ... Any fraction greater than zero of the infinite is still infinite. ... happens so as to minimise an approriate action: ... least resistance." ...
    (rec.photo.digital.slr-systems)
  • Re: Time Step too small in EWB
    ... Standard spice inductors have zero resistance, ... which means they have infinite Q. These two components ...
    (sci.electronics.design)
  • Re: Simple Question
    ... Now if you connect an infinite number of resistors in parallel, ... get zero ohms, no matter how large they are. ... resistance will be very, very small - so small that you might not even ... PCBs, or an infinitely large copper sheet, if you like. ...
    (sci.electronics.basics)
  • Re: Simple Question
    ... If there existed and infinite two dimewnsional array of 1 ohm resisters, ... what is the resistance between two point seperated by a knights move (i.e. ... with white and black squares ... mean of the surrounding four nodes. ...
    (sci.electronics.basics)
  • Re: Can twisted wire replace shielded wire?
    ... >>> Characteristic impedance and DC resistance are the same if the line is ... > of an infinitely long line, it's not bullshit, it's perfectly true, even ... There's no way an infinite length will have a lower resistance. ...
    (sci.electronics.basics)