magnetic-flux in iron

例句：

1. 1. The magneticflux in the coil ismeasured by a sensitive instrument.
   线圈中的磁通量通过一台敏感仪器进行测量。
2. 2. The magnetic flux density is directlyproportional to the strength of the magnetic field.
   磁通密度与磁场强度成正比。
3. 3. Themagnetic flux density is affected by theshape and size of the coil.
   线圈的形状和大小会影响磁通密度。