[領域]普通物理電學

[來源]課本習題

[題目]Careful measurement of the electric field in the ground can help provide
      useful information about charge. In a particular region, a technician
      has determinded that the electric field in a cubical volume, 1.00m on a
      side, is
      E=E0(1+ z/a)i+E0(z/a)j (i,j是向量)
      where E0=1.00N/C and a=1.00m. The cube has its sides parallel to the
      coordinate axes,Fig. 22-43. Determine the net charge within the cube.
      圖：http://0rz.tw/922we

[瓶頸]其實我不太懂題目，所以也不知道該怎麼寫/______\


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