一个矩形线圈在匀强磁场中匀角速度转动，产生的交变电动势的瞬时表达式为e=10
sin4πtV，则：
A．该交变电动势的频率为2Hz
B．t=0s时刻线圈平面与磁场平行
C．t=0.25s时，e达到最大值
D．在1s时间内，线圈中电流方向改变100次
答案：A
本题考查的是交流电的相关问题，根据交流电表达式可知，该交变电动势的频率为2Hz，A正确；t=0s时刻线圈平面与磁场垂直，B错误；t=0.125s时，e达到最大值，C错误；在1s时间内，线圈中电流方向改变2次，D错误；
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