A short time constant is defined as no more than _________ the pulse width, in time, for the applied voltage.

The correct answer is option 3):(one - fifth)

Concept:

• The time constant is defined as the measure of time required for certain changes in voltages and currents in RC and RL circuits.
• The elapsed time exceeds five-time constants (5τ) after switching has occurred, the currents and voltages have reached their final value, which is also called steady-state response
• A Pulse is a voltage or current that changes from one level to another and back again. If a waveform's high time equals its low time it is called a square wave. The length of each cycle of a pulse is its period 
• A short time constant is defined as no more than one-fifth the pulse width, in time, for the applied voltage.