Diathermy is defined as using which type of energy for therapeutic stimulation?

• A. High-frequency electromagnetic waves (>10 MHz)
• B. Sound waves
• C. Low-frequency electric current
• D. Visible light

Answer: (A)

Diathermy relies on deep tissue heating produced by high-frequency electromagnetic energy. This energy, in the radiofrequency range (above about 10 MHz), penetrates tissues and converts electric energy into heat as dipoles and charged particles respond to the rapidly alternating field. This dielectric or conductive heating effect warms deeper structures compared to other modalities, which explains its use for therapeutic heating.

Ultrasound uses mechanical sound waves, not electromagnetic energy, to generate heat and tissue effects. Low-frequency electric currents are primarily for electrical stimulation rather than heating, and visible light is optical energy used in other phototherapy approaches, not diathermy. So, the best description is high-frequency electromagnetic waves above 10 MHz.