Hi, I have a question about LPF and HPF in RC circuit.
I know that in LPF when τ>>t the capacitor is close to be a short.
but what happens in HPF when τ>>t ? that capacitor is close to be a short also?

Thanks for your help!

 

After T seconds very little current would be flowing through the capacitor, so it could be generalized as being open circuit.

 

After T seconds very little current would be flowing through the capacitor, so it could be generalized as being open circuit.

But in HPF when τ>>t the output signal is very similar to the input signal so it means that the capacitor is short and the input voltage pass to the output no?
I talks about this circuit:

 

Hi,

In the HPF, for very short times the output equals the input so the cap looks more like a short.
For very long times the output goes to zero so the cap looks like an open.

Looking at it from a frequency perspective, for high frequencies the cap looks like a short, and for low frequencies the cap looks open.

Since time is the inverse of frequency:
T=1/f

high frequency is similar to a short time period, where the period is relative to the RC time constant tau.