You've got to ask yourself, let the time it takes to do a full circle, that's the time period, do a full circle.

你已经问你自己了,留足够的时间让它运动一整圈,那就是运动整个圆周的时间周期

耶鲁公开课 - 基础物理课程节选

It makes sense to draw the wave function as a circle, because we do know that 1 s orbitals are spherically symmetric.

把波函数画成一个圆是有道理的，因为我们知道1s轨道是球对称的。

麻省理工公开课 - 化学原理课程节选