A $3$-phase $50$ Hz square wave ($6$-step) VSI feeds a $3$-phase, $4$ pole induction motor. The VSI line voltage has a dominant $5^{th}$ harmonic component. If the operating slip of the motor with respect to fundamental component voltage is $0.04$, the slip of the motor with respect to $5^{th}$ harmonic component of voltage is _________.