Each device that produces electric current produces both electric and magnetic field. Tissues will absorb more energy of electric or magnetic field, depending on chemical composition of tissue. Adipose tissue is an insulator and because of that it resists to electric current. This resistance will cause temperature rise of tissue. Adipose tissue offers no resistance to the magnetic field. If tissues, which contain many electrolytes, are subjected to the highfrequency magnetic field, it causes molecules in tissue to vibrate and produce heat. Consequently, absorption of the electric and magnetic field leads to increased temperature of the tissue, which leads to the increased blood circulation, muscle relaxation and pain relief. It also speeds up metabolism and the rate of ion diffusion across cellular membranes. Short wave diathermy machines use two condenser plates that are placed on either side of the body part to be treated. Another mode of application is by induction coils. When electromagnetic waves travel through the body tissues, they are converted into heat. The degree of heat and depth of penetration depend in part on the absorptive and resistance properties of the tissues. Microwave diathermy is considered to be the easiest to use. Physical effects are similar as those in short wave diathermy, but the microwaves have a relatively poor depth of penetration. Microwaves can cause hyperthermia in tissues. Hyperthermia induced by microwave diathermy raises the temperature of deep tissues from 41 °C to 45 °C, which produces short- term pain relief.