Today I found a wierd thing that as I removed the pin of the echo dot
And after this I removed the adapter from the power supply and found a wierd buzz sound coming from the adapter but as I connected this pin to Echo dot thinking that it would stop the sound and to my surprise The buzz sound faded with time and eventually died down.
So I know that the charged capacitor inside it is loosing its energy. But what is the mechanism after which it is creating this weird buzz sound?
PS- I have original adapter and the voltage supply in my area is also constant.
Please try to explain it simply I am a high school student