Which wavelength range is associated with short wave diathermy?

• A. 13, 27, or 45 MHz
• B. 2450 MHz
• C. 60 Hz
• D. 0.5-1 MHz

Answer: (A)

Short wave diathermy uses radiofrequency energy in the shortwave band, roughly 10 to 100 MHz. The frequencies most commonly used are about 13.56 MHz, 27.12 MHz, and around 40–45 MHz. Those frequencies correspond to wavelengths in air of roughly 22 m, 11 m, and about 6–7 m, respectively (tissue changes the actual wavelength, but the principle remains: SWD operates in this shortwave RF range). The other options fall outside this band: 2450 MHz is in the microwave region used for microwave diathermy, 60 Hz is the power line frequency, and 0.5–1 MHz is a much lower RF range not used for SWD.