We now analyze the i-v relationship of the three ideal circuit elements in light of the new phasor notation. The result will be a new formulation in which resistors, capacitors, and inductors will be described in the same notation. A direct consequence of this result will be that the circuit theorems of Chapter 3 will be extended to AC circuits. In the context of AC circuits, any one of the three ideal circuit elements defined so far will be described by a parameter called impedance, which may be viewed as a complex resistance. The impedance concept is equivalent to stating that capacitors and inductors act as frequency-dependent resistors, that is, as resistors whose resistance is a function of the frequency of the sinusoidal excitation. Figure 4.33 depicts the same circuit represented in conventional form (top) and in phasor-impedance form (bottom); the latter representation explicitly shows phasor voltages and currents and treats the circuit element as a generalized “impedance.” It will presently be shown that each of the three ideal circuit elements may be represented by one such impedance element.