Low pass filter ac dc etc

Hello

For some reason I have such a difficult time understanding how this works. I am aware of how to do the calculations for a time constant. I also know that a capacitor has an reactans XC which act as a resistor, and that at higher frequenzs the reactans will drop.


Questions:

Does a capacitor at a low frequenze have a longer time to charge? And how does this affect the capacitor and the reactans?

I dont get why it has to be ac and not dc. What if I had a frequnze of DC square waves?

I think I got it now :/ it quite confusing.

At low frequence it will have a longer time to charge the capacitor, and therefore the reactans (ohm) will increase, the capacitor will then be able to work as open ciruit and not let the low frequnze through. The low frequence will be lead to the output.

When using a high frequence, there is a shorter time to charge the capacitor before it begins discharging. Therefore it wont charge up the capacitor much and the reactans wont be high (ohm) throguh the capacitor tus leading high frequencies through the capacitor and nothing to the output.

Can anyone confirm this?