What term describes the circuit behavior immediately after an input change?

• A. Transient Behavior
• B. Steady-State Behavior
• C. Harmonic Behavior
• D. Static Behavior

Answer: (A)

Transient behavior is the circuit’s response right after the input changes. It happens because energy-storage elements like capacitors and inductors prevent instantaneous jumps in voltage or current, so the voltages and currents move from their previous values toward new steady values. This response often follows exponential curves with a time constant (RC for capacitors, L/R for inductors). For a simple RC step from 0 to V, the capacitor voltage climbs as Vc(t) = V(1 − e^(−t/RC)) and the current decays as i(t) = (V/R) e^(−t/RC). After enough time, the transient dies out and the circuit reaches steady-state, where values stay constant for a DC input. Harmonic behavior relates to sinusoidal inputs, and static behavior implies no time variation, so they don’t describe the immediate post-change response.