Question

An 800-kHz radio signal is detected at a point 4.5 km distant from a transmitter tower. The electric field amplitude of the signal at that point is 0.63 V/m. Assume that the signal power is radiated uniformly in all directions and that radio waves incident upon the ground are completely absorbed. What is the magnetic field amplitude of the signal at that point? (c = 3.0 × 108 m/s, μ0 = 4π × 10-7 T ∙ m/A, ε0 = 8.85 × 10-12 C2/N ∙ m2)

Answer 1

Answer:

$2.1\times 10^{-9} T$

Explanation:

We are given that

Frequency,f=800KHz=$800\times 10^{3} Hz$

$1kHz=10^{3} Hz$

Distance,d=4.5 km=$4.5\times 10^{3} m$

1 km=1000 m

Electric field,E=0.63V/m

We have to find the magnetic field amplitude of the signal at that point.

$c=3\times 10^8 m/s$

We know that

$B=\frac{E}{c}$

$B=\frac{0.63}{3\times 10^8}=0.21\times 10^{-8} T$

$B=2.1\times 10^{-9} T$