Electromagnetic Waves Physics Example 4

Solution

1. 1
   Frequency: $5 \text{ GHz} = 5 \times 10^9 \text{ Hz}$. Wavelength: $\lambda = \frac{c}{f} = \frac{3 \times 10^8}{5 \times 10^9} = 0.06 \text{ m} = 6 \text{ cm}$.
2. 2
   For uniform radiation in all directions, intensity decreases as $I = \frac{P}{4\pi r^2}$.
3. 3
   $$I = \frac{0.1}{4\pi(10)^2} = \frac{0.1}{1256.6} \approx 7.96 \times 10^{-5} \text{ W/m}^2$$