AC Adapter Making a Quiet Hum Noise in Europe

[MKC5527]

I bought my laptop in the US. I'm on vacation so I got a plug adapter and when I was in the UK everything was fine.

I'm in Belgium now, so I changed my adapter to the Europe plug, and when I plugged in my charging cord the AC Adapter started like...humming? When I the plugged it into my laptop the sound kind of changed...like still a hum but not as constant? Sorry I know that's an awful description. I unplugged it from my laptop and it went back to the original humming. When I unplugged it from the wall it was still making noise for just a few seconds. I don't think its never done that before and now I'm scared to use it because I don't want to ruin my charging cord or my laptop. 

I saw something about "coil whining" could this be what's happening? I can only hear the sound with the adapter literally pressed against my ear, I just don't think I've ever heard it before. 

I know that the input for my charger is 100-240, I know that Europe is 220. I just want to know if I'm being neurotic or if I should be concerned. 

I spoke to someone using the HP Chat but all they said was go to a store here and ask them.  However, I don't speak Dutch and I really don't want to waste a bunch of time in a store (if I can even find one here) if it's nothing to worry about.

[Lil_Boy_Blue]

Hi

Nice to know the UK has the better supply system.

The harmonised voltage, globally (with the ODD exception), is 230v 50 Hz. 

Some countries are slightly outside that, but within tolerance, and I suspect it is the 50 Hz part that is the problem in Europe.  

Note: if you hear a distinct hissing or high-pitched whistling instead of a buzz or scratch, that might be the altogether different phenomenon known as “capacitor squeal.” This is something to be concerned about, since it indicates a failing component.

So coil whine is unfortunate, but not detrimental.  I would proceed with caution.