1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

puzzle

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by pebe, Dec 23, 2002.

  1. pebe

    pebe Member

    Joined:
    Sep 24, 2002
    Messages:
    354
    Likes:
    1
    Location:
    Ellon - Scotland
    :) Just a little light hearted puzzle to keep the grey matter active over Christmas when you are not busy with the soldering iron!

    A plastic cube has a 10ohm resistor laid along each of its 12 edges. At each corner the ends of the three meeting resistors are connected together.

    What is the resistance between two furthest corners? :?

    Happy Xmas to everyone.
     
  2. kinjalgp

    kinjalgp Active Member

    Joined:
    Oct 28, 2002
    Messages:
    1,851
    Likes:
    3
    Location:
    INDIA/USA
    The answer is 8.333 Ohms :)

    MERRY CHRISTMAS to all Forum Members!
     
  3. bogdanfirst

    bogdanfirst New Member

    Joined:
    Dec 13, 2002
    Messages:
    1,310
    Likes:
    1
    Location:
    Ramnicu Valcea, Romania
    hey, good question .....
    i used to do theses kind of problems at physics last year...
    it's not hard to calculate...
    first u resuce the cube to a pyramid, then o use the tranfiguartion from star to triangle and all u obtain is a simple group of paralel and series resistors..
    i don't know if the value is 8.333 ohms, i dont have time to calculate...
    but what i can tell u is that if u make the schematic and use a simulation progrma many would give u a wrog answer.....
     
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. pebe

    pebe Member

    Joined:
    Sep 24, 2002
    Messages:
    354
    Likes:
    1
    Location:
    Ellon - Scotland

    Bang on correct, both of you.

    Anyone any similar puzzles I can do over Xmas?
     
  6. kinjalgp

    kinjalgp Active Member

    Joined:
    Oct 28, 2002
    Messages:
    1,851
    Likes:
    3
    Location:
    INDIA/USA
    Ok Pebe try same puzzle with resistor value of 330 Ohm! 8)
     
  7. bogdanfirst

    bogdanfirst New Member

    Joined:
    Dec 13, 2002
    Messages:
    1,310
    Likes:
    1
    Location:
    Ramnicu Valcea, Romania
    try this, all th segments have the value R
     
  8. bogdanfirst

    bogdanfirst New Member

    Joined:
    Dec 13, 2002
    Messages:
    1,310
    Likes:
    1
    Location:
    Ramnicu Valcea, Romania
    how can i send a pic?
     
  9. bogdanfirst

    bogdanfirst New Member

    Joined:
    Dec 13, 2002
    Messages:
    1,310
    Likes:
    1
    Location:
    Ramnicu Valcea, Romania
    so stupid i was....
    here's another puzzle.all the segmants have the value R, find the value between the nodes[​IMG][/list]
     
  10. pebe

    pebe Member

    Joined:
    Sep 24, 2002
    Messages:
    354
    Likes:
    1
    Location:
    Ellon - Scotland
    Without a calculator to hand - so done in my head, I think it's 275ohms.
     
  11. kinjalgp

    kinjalgp Active Member

    Joined:
    Oct 28, 2002
    Messages:
    1,851
    Likes:
    3
    Location:
    INDIA/USA
    CORRECT :D
    It was easy ! For 10Ohm it was 8.33 so for 330 Ohm it will be 330*8.33/10 = 274.89 ~ 275 Ohms :)
     
  12. pebe

    pebe Member

    Joined:
    Sep 24, 2002
    Messages:
    354
    Likes:
    1
    Location:
    Ellon - Scotland
    I can't see what the "[​IMG][/list]" is. Can you describe which nodes?
     
  13. bogdanfirst

    bogdanfirst New Member

    Joined:
    Dec 13, 2002
    Messages:
    1,310
    Likes:
    1
    Location:
    Ramnicu Valcea, Romania
    i cant post a picture of the schematic.....
    i used cut+imc here and it still doesnt work....
    somebody tell me how to place a picture in tthe answer....
     
  14. bogdanfirst

    bogdanfirst New Member

    Joined:
    Dec 13, 2002
    Messages:
    1,310
    Likes:
    1
    Location:
    Ramnicu Valcea, Romania
  15. kinjalgp

    kinjalgp Active Member

    Joined:
    Oct 28, 2002
    Messages:
    1,851
    Likes:
    3
    Location:
    INDIA/USA
    You have to first store the picture on internet. You can store it on free web space like geocities. The type the URL of your file between "img" tags.
    Like [​IMG]
     
  16. Phasor

    Phasor Member

    Joined:
    Aug 14, 2002
    Messages:
    703
    Likes:
    0
    Location:
    Sydney, Australia
    I might just mention that this is certainly not a new puzzle. I have seen it published in ETI, about 1974.
     
  17. kinjalgp

    kinjalgp Active Member

    Joined:
    Oct 28, 2002
    Messages:
    1,851
    Likes:
    3
    Location:
    INDIA/USA
    Ok lets see if some one can find what the equivalent resistance be between terminals A and B. I want calculation steps and not only final answer :) . Terminal B is in the lower right corner which is not visible in the schematic.
    [​IMG]
     
  18. bogdanfirst

    bogdanfirst New Member

    Joined:
    Dec 13, 2002
    Messages:
    1,310
    Likes:
    1
    Location:
    Ramnicu Valcea, Romania
    u wanta calculatons...
    ok
    from what i ses there is a square and 2 diagonals....the 2 other corners apart from A and B are at the same potential so there is no current flawing drom the resistance that unites them can be eliminated.....
    now, a square and a diagonal from a to b....
    unite the points with the same potential and u get a triangle....
    turn the triangle in a star and trough one of the resistors is not flawing current, so there are only 2 250 ohm resistors...
    so the value is 500 ohms?
    (p.s. i mistake most of the time when it comes to mathematical calculations, so this might not be an exception)
     
  19. bogdanfirst

    bogdanfirst New Member

    Joined:
    Dec 13, 2002
    Messages:
    1,310
    Likes:
    1
    Location:
    Ramnicu Valcea, Romania
    another puzzle....
    try the one above with capacitors......1uF
     
  20. kinjalgp

    kinjalgp Active Member

    Joined:
    Oct 28, 2002
    Messages:
    1,851
    Likes:
    3
    Location:
    INDIA/USA
    Correct 500 Ohm is the right answer. :)
     
  21. pebe

    pebe Member

    Joined:
    Sep 24, 2002
    Messages:
    354
    Likes:
    1
    Location:
    Ellon - Scotland
    Resistance = infinite (or as determined by the leakage)
    Capacity = 2uF
     

Share This Page