GbEng
检流计，电流计一种仪器，用以探测、测量和测定微小电流方向，采用线圈在磁场中产生的机械效果的方法 An instrument used to detect, measure, and determine the direction of small electric currents by means of mechanical effects produced by a coil in a magnetic field.
指南针用于确定地理方向的设备，通常包括一个或多个水平安装或悬挂的磁针，可在枢轴上自由活动直到与地球磁场在一条线上 A device used to determine geographic direction, usually consisting of a magnetic needle or needles horizontally mounted or suspended and free to pivot until aligned with the magnetic field of Earth.
磁控管一种微波管，它里面的发热阴极发出的电子受到磁场和电场的影响，从而产生能用于雷达和微波炉微波辐射 A microwave tube in which electrons generated from a heated cathode are affected by magnetic and electric fields in such a way as to produce microwave radiation used in radar and in microwave ovens.