To achieve zero phase difference between current and voltage in an AC circuit with an inductor and resistor, two methods can be employed. The first method involves adding a capacitor in series with the inductor to cancel out the inductive reactance. The second method, which is less understood, suggests adding another resistor to adjust the total impedance while maintaining the current at 0.2 A. The discussion reveals some confusion regarding the role of the additional resistor, but it ultimately clarifies that the capacitor is responsible for eliminating the phase shift, while the resistor adjusts current levels. Understanding these concepts may require further study of complex numbers and power triangles in AC circuits.