The coil opposes the flow of ac current, as a resistor does in a dc circuit.
XL. It is measured in ohms. Ohm's Law can be applied, as in the top formula.
f is the frequency of the applied voltage, and L is the value of the coil in Henries.
It can be seen from this formula that the value of
XL goes up as the frequency increases. It also goes up if the value of the coil increases.
This means that as the value of L or f increases, the opposition to the flow of ac