polarity of transformer

例句：

1. 1. The polarity of the current is 10 A.
   电流的极性是10安培。
2. 2. The polarity of the current is opposite to that of the other wire.
   电流的极性与另一根电线的极性相反。
3. 3. The polarity of the current is determined by the direction of the magnetic field.
   电流的极性由磁场的方向决定。