To solve the exercise it is necessary to take into account the concepts of wavelength as a function of speed.
From the definition we know that the wavelength is described under the equation,

Where,
c = Speed of light (vacuum)
f = frequency
Our values are,


Replacing we have,



<em>Therefore the wavelength of this wave is
</em>
Inductive reactance (Z) = ω L = 2Πf L = (2Π) (12,000) (L)
I = V / Z
4 A = 16v / (24,000Π L)
Multiply each side by (24,000 Π L):
96,000 Π L = 16v
Divide each side by (96,000 Π) :
L = 16 / 96,000Π = 5.305 x 10⁻⁵ Henry
L = 53.05 microHenry