Which modality heats by converting high frequency electromagnetic energy into heat?

• A. Ultrasound
• B. Infrared lamp
• C. Diathermy
• D. Fluidotherapy

Answer: (C)

Heating by converting high-frequency electromagnetic energy into heat operates through diathermy. It uses radiofrequency energy that penetrates tissues, and as the electromagnetic field interacts with tissue, the induced currents and dielectric losses generate heat inside the tissues, warming deeper structures. Ultrasound heats by turning mechanical energy (sound waves) into heat through tissue friction, not by electromagnetic energy. An infrared lamp emits radiant energy that is mostly absorbed at the surface, producing superficial warmth rather than deep heating. Fluidotherapy heats through convection of warm particles, without relying on electromagnetic energy. So the modality that converts high-frequency electromagnetic energy into heat inside tissues is diathermy.