Explain why the reactance offered by an inductor increases with increasing frequency of an alternating voltage.

When a current passes through the inductor, magnetic field is created due to the inductor coil. According to Lenz’s law this current give rise to back Emf which opposes the rise in current. Thus acts like a resistance. Hence, more the rate of current flow more the back emf thus more the resistance.
This means that increase in frequency increases the inductive reactance.
Inductive reactance is given as
X_L=2πfL
Where, X_L is the inductive reactance, f is the frequency of the supply voltage and L is the inductance.
We can see that Inductive reactance and frequency have direct relationship
Hence, the reactance offered by an inductor increases with increasing frequency of an alternating voltage.