Answer:
[tex]2.1\times 10^{-9} T[/tex]
Explanation:
We are given that
Frequency,f=800KHz=[tex]800\times 10^{3} Hz[/tex]
[tex]1kHz=10^{3} Hz[/tex]
Distance,d=4.5 km=[tex]4.5\times 10^{3} m[/tex]
1 km=1000 m
Electric field,E=0.63V/m
We have to find the magnetic field amplitude of the signal at that point.
[tex]c=3\times 10^8 m/s[/tex]
We know that
[tex]B=\frac{E}{c}[/tex]
[tex]B=\frac{0.63}{3\times 10^8}=0.21\times 10^{-8} T[/tex]
[tex]B=2.1\times 10^{-9} T[/tex]