Do This:

1. Adjust the Frequency of the input signal. Notice once it exceeds the cutoff frequency of the Ideal Lowpass the output signal goes to 0.
2. On the bottom right, change the Filter Choice to Highpass Ideal and adjust the input frequency. What happens?
3. Try also the Ideal Bandpass filter.
4. Try the Averaging Filter. What affect does the magnitude have on the output as frequency changes? What affect does the phase have?
5. The demo also has non-ideal filters. Play with them. How do they differ from the ideal ones?