Step Response of an RC Circuit – Derivation of Complete Response involves analyzing the behavior of a resistor–capacitor (RC) circuit when subjected to a step input voltage. By applying Kirchhoff’s Current Law and the capacitor current–voltage relationship, a first-order differential equation is obtained. Solving this equation yields the complete response, which consists of the natural response and the forced response. The resulting expression describes the exponential charging or discharging behavior of the capacitor and illustrates the effect of the time constant on the transient and steady-state performance of the circuit.