Using Ampere's Law, the magnetic field produced inside this solenoid is given by
B = uo N I / h
where uo is the vacuum permeability, N is the number of turns in the solenoid and h is the length of the solenoid. Earth's magnetic field is around 50 microteslas in North America thus the current needed in the solenoid is
I = B h / (uo N) = (50 E-6 ) (4) / ((4 pi E-7)(6000) ) = 0.026 A
I = 26 mA
So you need a current of around 26 mA.
Answer:
2.83 m
Explanation:
The relationship between frequency and wavelength for an electromagnetic wave is given by

where
is the wavelength
is the speed of light
is the frequency
For the FM radio waves in this problem, we have:
is the minimum frequency, so the maximum wavelength is

The maximum frequency is instead

Therefore, the minimum wavelength is

So, the wavelength at the beginning of the range is 2.83 m.
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