RC cutoff frequency
Bigger R or C means a longer response time and a lower cutoff. The corner is a gentle bend, not a brick wall.
f = 1 / (2πRC)
Ideal first-order RC low-pass or high-pass, driven by a zero-impedance source with no output loading. At cutoff, amplitude is 1/√2 (about 70.7%). Component tolerances shift the cutoff.