You have done several labs that involved filters.  From your work in lab answer the following questions.

• What is a low-pass filter?
• Why was it used to filter the pressure sensor voltage?
• What effect did it have on the audio signal (from the CD?)
• What do these two situations have in common?
• What limitations are there for the particular low-pass filters you used?
• What is the approximate range of frequencies passed for the filter for the audio signal?  What frequencies tend to be rejected?
• What is the difference between a high-pass and a low-pass filter?  Draw upon your experience with the audio signal.
• In using the low-pass filter, the filter did not perform well when the filter output was used directly with the headphones.  You needed an operational amplifier.  Explain the function of the amplifier and why it was necessary.