Referring to Fig. 17.58, determine the collector current above which the switching time does not change appreciably

Question:

Referring to Fig. 17.58, determine the collector current above which the switching time does not change appreciably for RL = 1 k(, and RL = 100(.
b. At IC = 6 mA, how does the ratio of switching times for RL = 1 k( and RL = 100 ( compare to the ratio of resistance levels?