Higher wattage infrared sources tend to penetrate deeper into tissues.

• A. True
• B. False
• C. Not enough information
• D. Only at high frequencies

Answer: (A)

Higher wattage in infrared therapy increases the amount of energy delivered to the tissue per unit time. That extra energy heats not only the surface but can be conducted and diffused into deeper layers, producing a meaningful heating effect in tissues below the surface. While the exact depth at which photons preferentially travel is mainly determined by wavelength and tissue properties, the greater energy input from a higher wattage source tends to extend the practical depth of heating and therapeutic effect. So, in practice, higher power infrared sources can produce deeper heating, making the statement true.