5L30.30 - Circuit Filters

Code Number:
Demo Title:
Circuit Filters
AC Circuits
Area of Study:
Electricity & Magnetism
Capacitance Box, Resistor Box (Carbon Resistors), Wave Generator (Wavetek), Oscilloscope, Frequency Counter (if desired), and Homemade Inductors, 9 Volt Batteries, Passive and Active High and Low Pass Filter Circuits.

Passive and Active High-Pass and Low-Pass filters are available for demonstrations as shown.  You will need to connect two 9 Volt batteries to each Active filter circuit. 

Arrange the filter as shown and as described in McCliment's Textbook, page 603, exercise 33 & figure 18-52.  Use the frequency range from 0 to 110 KHz.  The resistor box can be set from between 470 to 1500 ohms, and the capacitor at .1 microfarads.  Set the wave generator to sweep the frequencies in a 10 second sweep if desired.  Observe how the low frequencies are passed and the higher frequencies are filtered out.

A high pass filter may be made by substituting an inductor in place of the capacitor.  The frequency range will be from 0 to 13 MHz.  This can be achieved by setting the wave generator mode to the 'Set' position.  The resistor box can be set from 1000 to 6800 ohms.  As you sweep the frequency range there will be several places in the range where the frequencies will pass freely (Around 6 MHz. and from 10 to 13 MHz).

This circuit is used to demo Craig Kletzing's clicker question.


  • Erik Zavrel, Eric Sharpsteen, "Introducing Filters and Amplifiers Using a Two-Channel Light Organ", TPT, Vol. 53, #8, Nov. 2015, p. 478.
  • Yaakov Kraftmakher, "1.15 Electrical Filters", Experiments and Demonstrations in Physics, ISBN 981-256-602-3, p. 58.

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