I have to do laboratory report for electronics, the laboratory is about the simple BJT inverter circuit. The circuit consists of one RB = 6.8 k (base resistor), one RC = 1 k (collector resistor), and one transistor 2N2222. A 10 kHz TTL signal (from the TTL output of the Function Generator) is supplied to VIN, and the output waveform is observed on the oscilloscope. Then this experiment is repeated for RC = 10 K.

After I observed the waveforms, the switching time for circuit with RC = 1 K is less than the switching time for the circuit with RC = 10 K.

But I get stuck with this question, why the RC value affects the switching time of the output voltage, I've been searching in my textbook and also over the internet, but I still can not understand why.....

Please help me...I have to submit my report in 3 days.

Thank you very much for your help