Why does charging time scale linearly with RC if the voltage curve is exponential?

[jaejoon89]

Why is time in a series RC circuit linearly dependent on capacitance as charging/discharging time is increased? (same with resistance) I thought RC circuits were exponential.

 

[turin]

Please don't think I'm being rude. I'm just picky. I want to be helpful, but I'm getting sleepy, so this will be terse.

Why is time in a series RC circuit linearly dependent on capacitance as charging/discharging time is increased?

I can only assume that you mean "time constant" for the first "time" in this sentence. This is just a consequence of the very simple definition.

I thought RC circuits were exponential.

This doesn't mean anything. Perhaps you mean that the dependence of the value of some electrical property depends exponentially on time?

 

[Redbelly98]

Or to put it another way:

The voltage and current are exponential functions of time.

The time required for the voltage or current to reach a specific value is proportional to RC. For example, the time in which the capacitor voltage reaches 50% of its final value.