Typical frequencies for devices generating intermediate frequency fields

Intermediate frequency fields	300 Hz - 100 kHz
anti-theft devices	ranging from some tens of Hz to a few GHz depending on the type of system
induction hobs and hotplates	20 to 50 kHz
electric engines and badge readers	about 100 kHz
Radio transmitters operated in the long wave range	30 kHz to 300 kHz
Welding devices	up to a few 100 kHz
Induction heaters	some tens of Hz to some tens of kHz
Electrosurgery systems	some hundred kHz
clinical MRI devices use intermediate frequency fields in addition to static and radio frequency fields	up to 10 kHz

Source: SCENIHR  Possible effects of Electromagnetic Fields (EMF) on Human Health