Question: What is the primary use of an active low-pass filter using an op-amp?

Options:

1. To amplify high-frequency signals
2. To allow low-frequency signals to pass while attenuating high frequencies
3. To rectify AC signals
4. To provide isolation between circuits

Correct Answer: To allow low-frequency signals to pass while attenuating high frequencies

Solution:

An active low-pass filter allows low-frequency signals to pass while attenuating high-frequency signals, using an op-amp for gain.