A sinusoidally driven circuit containing an inductor and a resistor has a response given by

where is the peak amplitude, is the driving angular frequency, and is a phase shift from the phase of the source. The (complex) current can be found as

where Z is the total impedance, is the permittivity of free space, L is the inductance, R is the resistance, and is the angular frequency. The phase difference is then

with peak current given by