佑信 asked in 科學其他:科學 · 8 years ago

磁場 - 磁針方向

將一個水平羅盤放置於距離某垂直導線18cm之正南方的位置,若導線帶有垂直向下之43A的電流,求羅盤之磁針N極所指的方向。假設地球磁場之水平分量大小為

圖片參考:http://imgcld.yimg.com/8/n/AD08476829/o/7012051500...

,另外請忽略地球磁場之垂直分量的作用。

1 Answer

Rating
  • 天同
    Lv 7
    8 years ago
    Favorite Answer

    Magnetic field produced by the current carrying wire at position of compass

    = (4.pi.10^-7) x 43/(2.pi x 0.18) T = 4.78x10^-5 T

    By right-hand-grip rule, the field direction is pointing west

    Therefore, when combining with earth's magnetic field, which is pointing north, the direction of the resutant field

    = arc-tan(4.78x10^-5/0.45x10^-5)

    = 84.6 degrees

    The compass needle points in direction 84.6 degrees west of north.

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