Permanent magnetic device. as a new type patent device, is used to ensure the hydroelectric generator to start its static excitation more reliably and more quickly.

永磁装置是一种用于使水轮发电机静止励磁系统可靠快速起励的新型专利装置。

youdao

A compass is a device containing a metal object that points toward the magnetic north pole.

VOA: special.2010.07.14

An electro-magnetic device known as an EM-Bird has also been flown, suspended beneath a helicopter, in long sweeps over the ice.

BBC: Arctic ice melting at 'amazing' speed, scientists find

California-based HPV Technologies recently demonstrated a "magnetic acoustic device" or MAD that can broadcast a targeted beam of sound for a more than mile.

NPR: Focused Sound 'Laser' for Crowd Control

Then, this device would make sound, because it has magnetic field like light streaming.

CNN: Interview with Nelson Shin