direct electromotive force

例句：

1. 1.The direct electromotive force is the force that drives the flow of electricity through a circuit.
   直接的电磁力是驱动电流通过电路流动的力量。
2. 2. The indirect electromotive force is the force that opposes the direct electromotive force and causes the current to flow in the opposite direction.
   间接的电磁力是与直接的电磁力相反的力量，导致电流以相反方向流动。
3. 3. The measurement of the direct electromotive force is important for understanding the behavior of electrical devices.
   直接的电磁力的测量对于理解电气设备的行为非常重要。