Why does an Electromagnet Vibrate ??? whenever any iron plate or steel spoon is placed near permanent magnet(not of very high strength) it gets attracted towards it and when it is removed from it it removes easily without any vibration effects. but if the same thing is performed with electromagnets then we experience a vibration in the spoon both during attraction and during removal of spoon from the field. Also a light humming sound is also there. why does this vibration happens ?? is there any way to remove this vibration effect in case of electromagnets and let it behave like permanent magnets? also if AC supply is used in electromagnets(in place of DC supply) then this vibration effect and humming sound is more. what is the reason behind this phenomenon??