The resistance of a conductor varies directly with its length, conversely with its cross-sectional area.
导体的电阻与其长度成正比，与其横截面积成反比。
2
C is a second coil formed by a conductor of much larger size and smaller length, wound around and in proximity to coil a.
是一个次极线圈，由相当大的尺寸和较小的长度构成，环绕与线圈a接近。
3
Therefore it is possible to simply regard the value of the induction on unit length in the near middle of two "infinite length" parallel conductor as its approximate value.