User Tag List

Page 1 of 19 1 2 3 11 ... LastLast
Results 1 to 10 of 188

Thread: Infinite Resistance

  1. #1
    Join Date
    Apr 2003
    Posts
    5,156
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Infinite Resistance

    I don't know if anybody's particularly interested in this, but.

    Another thread got me thinking about if V/R=0[zero]. When V is not zero.

    In other words no current flows from a voltage source with nothing connected across it.

    So to find the value of R, R=V/0[zero].

    So the divide by zero illegal function comes up. I've always prefered to think division by zero to equal infinity. Which would satisfy this equation (as it would many others). 1/(10 to the -23) is a big number.

    The smaller the divisor the larger the quotient. Until, reasonably, you reach X/0=infinity.

    The only problem I see is that infinity times zero is not a rational argument. But if that's the case why not put the illegal function there instead of at divide by zero?

    I know you're at least raising an eyebrow Charlie B.
    Sam, San Francisco Bay Area

  2. #2
    Join Date
    Nov 2004
    Posts
    3,610
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Re: Infinite Resistance

    physis,

    I think the mathematicians say that division by zero is undefined, that is, it is meaningless. However, there is also the matter of a ratio approaching a limit of infinity as the divisor approaches zero. Having said that, I think most wire twisters would say, "Who cares?", or "What does the code say?"

    The upshot of this is that you cannot compute the IR drop across an infinite resistance.

    [ December 06, 2004, 05:41 PM: Message edited by: rattus ]
    Don't mess with B+!
    (Signal Corps. Motto)

  3. #3
    Join Date
    Apr 2003
    Posts
    5,156
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Re: Infinite Resistance

    Well rattus, hence line one.

    I've tried to find an answer that I would be happy with more than a few times but have never been satisfied.

    I think it's that the answer is always something like, the rules of convention dictate, blah blah. And it's been defined. Honestly I don't even remember the explainations anymore.

    It just seems the closer the divsor to zero the closer the quotient to infinity.

    The problem is that infinity is a concept that can't be given a rational value and therefore isn't math. But at the same time there's a similar situation with pi. It's an irrational number but we know it's real (not as an integer) because we understand the relationship it represents.

    Edit: Divide by zero and infinity, to me, seem to be a similar relationship.

    [ December 06, 2004, 06:00 PM: Message edited by: physis ]
    Sam, San Francisco Bay Area

  4. #4
    Join Date
    Apr 2003
    Posts
    5,156
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Re: Infinite Resistance

    And how do we recocile no connection across a voltage source if we can't have infinite resitance?
    Sam, San Francisco Bay Area

  5. #5
    Join Date
    Nov 2004
    Posts
    3,610
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Re: Infinite Resistance

    Physis, how close can you get to infinity? I say close enough. And for practical purposes, there is such a thing as an infinite resistance. But how would you color code such a resistor?
    Don't mess with B+!
    (Signal Corps. Motto)

  6. #6
    Join Date
    Apr 2003
    Posts
    5,156
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Re: Infinite Resistance

    We use terms like infinite gain to describe an ideal OP amp and infinite impedence to describe radio circuits. It's almost common place in electrical engineering.

    how would you color code such a resistor?
    That's just it, it isn't a number. But I think you can say it's a value. So put that in your atom smasher.

    Edit: I don't think you can even color code .0001Ω

    [ December 07, 2004, 12:14 PM: Message edited by: physis ]
    Sam, San Francisco Bay Area

  7. #7
    Join Date
    Feb 2003
    Location
    Indianapolis
    Posts
    6,102
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Re: Infinite Resistance

    You know, this reminds me of the attempt to reach the speed of light in a collider. The faster they accelerate ions, the more energy is required to get them going faster. The mass continues to increase towards infinity and the amount of energy goes towards infinity as more speed is obtained. It is impossible to get to the speed of light because the faster an object goes, the more mass it gains and the more energy it takes to accelerate it. The bottom line is that sub-light is the only possibility and warp one or greater ain't a gonna happen. Sorry, impulse power only to visit the stars.
    Charlie Eldridge, Indianapolis, Utility Power Guy
    Responses based on the 2011 NEC, unless stated otherwise.

  8. #8
    Join Date
    Feb 2003
    Location
    Portage, Indiana NEC: 2008
    Posts
    9,911
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Re: Infinite Resistance

    Beam me up Charlie
    Wayne A. From: N.W.Indiana
    Be Fair, Be Safe
    Just don't be fairly safe

  9. #9
    Join Date
    Feb 2003
    Location
    Portage, Indiana NEC: 2008
    Posts
    9,911
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Re: Infinite Resistance

    By Sam: Another thread got me thinking about if V/R=0[zero]. When V is not zero
    Your right It's not v = 0 as it is I = 0
    And this is the mathematical formula for a broken wire at a light switch.
    Wayne A. From: N.W.Indiana
    Be Fair, Be Safe
    Just don't be fairly safe

  10. #10
    Join Date
    Apr 2003
    Posts
    5,156
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Re: Infinite Resistance

    The mass increases to infinity at C and you can't do it because it takes infinite energy to accelerate an infinite mass. Some genious must have assumed we don't have infinite energy.

    You can acheive I=zero with V=zero/R
    Sam, San Francisco Bay Area

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •