在电磁感应现象中感应电流受到的安培力往往是变力,这个变力的作用效果可以产生加速度,也可以对时间累积产生冲量改变导体棒的动量,也可以对位移累积产生功改变导体棒的动能,瞬时安培力产生瞬时加速度,大多数同学可以理解,也容易求解。但对安培力的冲量和安培力做功,很多同学就模糊不清,不知道能不能用变力的平均值乘时间求冲量或者用变力的平均值乘位移求做功?对这一点,有些教师也不清楚是对还是错,有些教辅用书上也武断地下结论:可以用安培力平均值乘时间求冲量I=F_At,但不能用安培力平均值乘位移求功W≠F_Ax。笔者觉得很有必要对这个 In the electromagnetic induction phenomenon, the ampere force induced by the induced current is often a variable force, the effect of this variable force can produce acceleration, impulse can also be accumulated over time to change the momentum of the conductor bar, Momentum, instantaneous ampere instantaneous acceleration, most students can understand, but also easy to solve. However, Ampere force impulse and Ampere force work, many students vague, do not know if you can use the average value of variable time by impulse or use the average of variable force by displacement to do work? On this point, some teachers It is not clear whether it is right or wrong. Some supplementary books conclude with an arbitrary argument that the amperage average can be used to obtain the impulse I = F_At by time, but not by the amperage mean by the displacement W ≠ F_Ax. I think it is necessary to this