Boit-Savart law

例句：

1. 1.The Boit-Savart law states that the magnetic field lines are always directed towards the Earth's surface.
   布-萨瓦特定律指出，磁感线总是指向地球表面。
2. 2. This phenomenon is often explained by the Boit-Savart law, which states that the magnetic field lines converge at the Earth's surface.
   这种现象通常由布-萨瓦特定律来解释，该定律指出磁感线在地球表面汇聚。
3. 3. In this case, the Boit-Savart law applies, as the magnetic field lines converge at the Earth's surface.
   在这种情况下，布-萨瓦特定律适用，因为磁感线在地球表面汇聚。