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alfers101

  • 2 years ago

Please help: Calculate the electric field at the center of a square 52.5cm on a side if one corner is occupied by a +45uC charge and the other three occupied by -27uC charges.

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  1. baldymcgee6
    • 2 years ago
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    sounds like physics bud

  2. baldymcgee6
    • 2 years ago
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    but i will help you anyway. you just need to find the NET electric field.

  3. baldymcgee6
    • 2 years ago
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    if you want me to help. . .

  4. baldymcgee6
    • 2 years ago
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    Do you know the formula for electric field?

  5. alfers101
    • 2 years ago
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    is it E=F(R)/Q ??

  6. baldymcgee6
    • 2 years ago
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    \[E= kq/r^2\]

  7. alfers101
    • 2 years ago
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    okay. then?

  8. baldymcgee6
    • 2 years ago
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    |dw:1340433733455:dw|

  9. baldymcgee6
    • 2 years ago
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    does the question say the side length of the square is 52.5cm?

  10. alfers101
    • 2 years ago
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    The question say: "at the center of a square 52.5cm on a side if one corner is occupied by a +45uC charge..."

  11. baldymcgee6
    • 2 years ago
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    okay, i'm going to assume the "side length" is 52.5cm

  12. alfers101
    • 2 years ago
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    okay. i think it is the length.

  13. baldymcgee6
    • 2 years ago
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    |dw:1340433904871:dw|

  14. alfers101
    • 2 years ago
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    okay.

  15. alfers101
    • 2 years ago
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    hmm i think thats it.

  16. baldymcgee6
    • 2 years ago
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    you need the length from the corner to the charges. do you know how to find that?

  17. alfers101
    • 2 years ago
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    sorry i dont know.

  18. baldymcgee6
    • 2 years ago
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    okay, if we have the side length of 52.5cm, to find the diagonal length we multiply this by \[\sqrt{2}\]

  19. baldymcgee6
    • 2 years ago
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    can you do that?

  20. alfers101
    • 2 years ago
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    52.5 * sqrt of 2 ?

  21. baldymcgee6
    • 2 years ago
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    yes = ?

  22. alfers101
    • 2 years ago
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    74.24

  23. alfers101
    • 2 years ago
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    but why sqrt of 2 ?

  24. baldymcgee6
    • 2 years ago
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    because a square is in the form of x^2+y^2=2.. you can look into it later, and just trust me.

  25. alfers101
    • 2 years ago
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    okay sure.

  26. baldymcgee6
    • 2 years ago
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    haha, k... so that 74.25cm is the diagonal length, we divide this by 2 to give us the corner to center length

  27. alfers101
    • 2 years ago
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    its 37.12

  28. baldymcgee6
    • 2 years ago
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    okay so now we can use our formula.

  29. alfers101
    • 2 years ago
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    okay.

  30. baldymcgee6
    • 2 years ago
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    E=(kq)/r^2

  31. alfers101
    • 2 years ago
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    our k is 9x10^9 ?

  32. baldymcgee6
    • 2 years ago
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    close enough, in physics we typically use 8.99 x 10^9

  33. alfers101
    • 2 years ago
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    oh but can we use 9x10^9 ?

  34. baldymcgee6
    • 2 years ago
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    we have to calculate each individual electric field. sure, it is close enough.

  35. alfers101
    • 2 years ago
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    okay. then our Q is what? our R is 37.12 ?

  36. baldymcgee6
    • 2 years ago
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    our q is the charge, there are 4 different charges. +45uC and -27uC, -27uC, -27uC

  37. alfers101
    • 2 years ago
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    so we will use the four different charges? one by one?

  38. baldymcgee6
    • 2 years ago
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    we will do two separate computations as three of them will be the same (-27uC)

  39. baldymcgee6
    • 2 years ago
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    so lets get started

  40. alfers101
    • 2 years ago
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    okay sure lets get started

  41. baldymcgee6
    • 2 years ago
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    fill this in with what we know: E=(kq)/r^2

  42. baldymcgee6
    • 2 years ago
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    or just do it on you're calculator and tell me the two answers

  43. alfers101
    • 2 years ago
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    E=(9x10^9) (+45uC)/37.12 ?

  44. baldymcgee6
    • 2 years ago
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    close... E=(9x10^9*45E-6)/(37.12)^2 dont forget to square the denominator

  45. baldymcgee6
    • 2 years ago
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    and also remember the units for the charge is in micro coulombs

  46. baldymcgee6
    • 2 years ago
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    therefore 45E-6

  47. alfers101
    • 2 years ago
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    why is the exponent is -6 ?

  48. baldymcgee6
    • 2 years ago
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    i just told you, because the units are in uC

  49. baldymcgee6
    • 2 years ago
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    that little "u" mean E-6

  50. alfers101
    • 2 years ago
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    oh yeah

  51. baldymcgee6
    • 2 years ago
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    okay, so what your answer?

  52. alfers101
    • 2 years ago
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    then the C means coulombs?

  53. baldymcgee6
    • 2 years ago
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    correct

  54. alfers101
    • 2 years ago
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    0.00079

  55. baldymcgee6
    • 2 years ago
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    you used this? E=(9x10^9*45E-6)/(37.12)^2

  56. alfers101
    • 2 years ago
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    yup i did

  57. baldymcgee6
    • 2 years ago
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    well i'm afraid that is wrong, you must have typed it in wrong

  58. baldymcgee6
    • 2 years ago
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    http://www.wolframalpha.com/input/?i=%28%289x10%5E9%29%2845E-6%29%29%2F%2837.12%29%5E2

  59. alfers101
    • 2 years ago
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    let me check

  60. alfers101
    • 2 years ago
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    E means exponent right?

  61. baldymcgee6
    • 2 years ago
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    k dude, you take way to long. I need to sleep. You should get a value of 293.55 N/C for the +45uC and you should get -176.13 N/C for the -26uC

  62. alfers101
    • 2 years ago
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    its -27uC

  63. baldymcgee6
    • 2 years ago
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    right, -27uC still the same answer.

  64. baldymcgee6
    • 2 years ago
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    i think you should be able to do it from here.. i've been helping you for over an hour.

  65. alfers101
    • 2 years ago
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    okay thank you so much.

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