As wavelength increase, frequency decrease
The most useful would be a Journal article, many (not all) possess information enough to replicate the experiment in order to increase its validity and to collaborate with the scientific community.
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Explanation:
This problem can be solved by using the equation
B = (μ0*I)/(2π*r) ( 1 )
where μ0 is the magnetic permeability, I is the current in the wire and r is the distance to the wire, where the magnetic field B is calculated. The equation (1) says that a current in a wire produce a magnetic field in a distance r from the wire.
Part A
Taking into account that μ0 = 
By replacing in the equation ( 1 ) we have:

Part B
In tis case is only necessary to calculate B/Be (Be is the magnetic field of the earth), but taking into account that tha magnetic field of the earth must be in teslas.
1 gauss = 10^(-4) T
0.50 gauss = 0.50*(10^(-4)) T = 5*10^(-5) T
Hence, the proportion between B and Be:

Thus, it is only 9% of the magnetic field of the earth.
Answer: A) 7.5v
B) 75000v/m
C) 1.66×10^-11
D) 7.5v
E) 232500v/m
F) 5.15×10^-11
Explanation:
The potential difference will be the same for the two cases.
Please find the attached file for the solution