$($a$)$ If an op$-$amp has a slew$-$rate of $5$ V$/$s$,$ find the upper corner frequency for a pulse output voltage of $5$ V$,1\mathrm{.}5$ V$,$ and $0\mathrm{.}4$ V$.($b$)$ An op$-$amp with a slew rate of $8$ V$/$s is driven by a $250$ kHz sine wave. What is the maximum output amplitude at which slew$-$rate limiting is reached?