middle circle of the toroid

例句：

1. 1. The middle circle of the toroid is where the magnetic field is strongest.
   磁环中间的圆是磁场最强的区域。
2. 2. The design of the toroid isbased on the principles of electromagnetism.
   磁环的设计基于电磁学的原理。
3. 3.The middle circle of the toroid iscrucial for maintaining the stability of the device.
   磁环中间的圆对于保持设备的稳定性至关重要。