La dangerosité d’une onde électromagnétique dépend de deux facteurs:
- sa fréquence mesurée en Hertz (Hz)
- et sa puissance d’émission mesurée en Watts (W).
La mesure d'une onde électromagnétique s'effectue en évaluant:
- l'intensité du champ électrique mesurée en Volts par mètre (V/m),
- l'intensité du champ magnétique mesurée en Tesla (T)
- et la densité de puissance mesurée (en W/m²).
- A Tesla (T) measures the magnetic flux density (i.e. the strength of a magnetic field). One Tesla is defined as a magnetic flux of one Weber uniformly distributed over an area of one square meter (1 Wb/m²).
- Medical magnetic resonance imaging (MRI) units operate between 1.5-7 T.
- A typical refrigerator magnet has a magnetic field strength of approximately 0.001-0.01 Tesla (T).
- This is about 20-200 times stronger than the Earth's magnetic field strength of 50 µT (microtesla) or 0.00005 T.
- Power density, measured in Watts per square meter (W/m²), quantifies the power (energy per unit of time) distributed over a given area.
- Solar power received is approximately 1'365 W/m² at high atmosphere or 1'000 W/m² at ground level.
- A modern Photovoltaic solar panel has a nominal power density of approximately 200-250 W/m².
- The heating power required domestically is often estimated between 70-100 W/m².
