Question
What is one way that RF energy can affect human body tissue?
Answer Options
- A) It heats body tissue
- B) It causes radiation poisoning
- C) It causes the blood count to reach a dangerously low level
- D) It cools body tissue
Correct Answer: A
Explanation
The primary way that high-frequency Radio Frequency (RF) energy affects human body tissue is through heating. Biological tissue is electrically conductive and acts like a lossy dielectric. When exposed to RF fields, current is induced in the tissue, and because the tissue has resistance, energy is dissipated as heat.
While low levels of RF exposure are harmless, excessive exposure, particularly at frequencies where the body can absorb energy efficiently, can cause localized heating. At HF frequencies, where the human body is roughly a half-wavelength long, the body is resonant and absorbs more RF energy as heat. At high UHF frequencies, heating comes primarily when the frequency is close to the resonant frequency of water molecules themselves; microwave ovens generate RF in the high UHF range for this reason.
More details on heating by RF absorption.
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