What's the matter with the buzzing sound of the laptop power adapter?

Students who have used notebooks know that sometimes when charging, the power adapter of the notebook will make a buzzing sound, sometimes it is very small, sometimes it is very loud, what's the matter? Some people even got scared when they heard the sound. Will the computer explode when it is fully charged? Today I will take you to find out.

In fact, the buzzing sound in the power adapter is the sound of the inductance coil vibrating due to the action of the magnetic field when the alternating current passes by. The inductance coil is generally packaged with paint seal, epoxy resin, heat shrinkable tape, etc. Generally, if the enameled wire winding packaging process passes the standard, It can well seal and isolate the sound generated by the vibration of the inductance coil, and the inductance sound will be very small. Of course, if the enameled wire winding packaging process of the power adapter is not good enough, or the packaging material becomes loose after a long time of use, it cannot be sealed to isolate the inductance The sound produced by the vibration of the coil will hear a loud buzzing sound.
If the sound of the power adapter fluctuates when it is working, it may be that the upstream device of the inductance is short-circuited. In this case, danger may occur, such as a short-circuit in a notebook or a spark at the plug.