Why do exposure limits vary with frequency?
Lower frequency RF fields have more energy than higher frequency fields
This answer is incorrect because, in reality, lower frequency RF fields generally have less energy per photon compared to higher frequency fields.
Lower frequency RF fields do not penetrate the human body
This answer is incorrect because lower frequency RF fields can indeed penetrate the human body, although the depth of penetration varies with frequency.
Higher frequency RF fields are transient in nature
This answer is incorrect because higher frequency RF fields are not transient in nature; they are continuous waves when used in communication.
The human body absorbs more RF energy at some frequencies than at others
This answer is correct as the human body does absorb more RF energy at certain frequencies, and this variation directly influences the exposure limits set for different frequencies.
Explanation
The question ‘Why do exposure limits vary with frequency?’ addresses the critical aspect of human safety concerning radio frequency (RF) exposure. RF exposure limits are guidelines set by regulatory bodies like the Federal Communications Commission (FCC) and the American National Standards Institute (ANSI) to protect individuals from potential health effects due to prolonged or excessive exposure to RF energy.
The correct answer is ‘The human body absorbs more RF energy at some frequencies than at others,’ highlighting the fact that the absorption rate of RF energy varies depending on the frequency. This variability is due to the resonance effect of the human body, where certain frequencies can penetrate tissue and be absorbed more efficiently than others, potentially leading to higher thermal or other biological effects. Ensuring compliance with these limits is crucial for amateur radio operators to avoid health risks and adhere to legal regulations.
T0C05 2022-2026