 # Exam Question Checklist

## Exam 1999 Question 4

"Explain what is meant by the frequency response of a system. Describe an experiment in which the frequency response of a simple resonator is measured. How is the bandwidth of a simple resonator related to the rate of energy lost from the resonator during vibration?"

20 things you should mention:

• Frequency Response
• tells us how the system deals with signals passed through it
• response is ratio of output amplitude to input amplitude
• can measure it for some frequencies using a sinusoid at that frequency
• frequency response graph is a graph of the response - axes
• - measured for different sinusoidal frequencies
• what system can do to a signal / examples / pictures
• natural resonant frequency
• Measurement
• e.g. an acoustic resonator/pendulum
• input: sinusoid generator
• fixed amplitude, variable frequency
• pass through system, e.g. loudspeaker, microphone
• output: millivoltmeter
• calculate response, express in dB
• plot graph, example picture
• measure bandwidth
• - from 3dB points
• Bandwidth/Time response
• wide bandwidth = wide range of frequencies giving moderate response
• rapid loss of energy from system, high damping
• narrow bandwidth = narrow range of frequencies giving large response
• energy retained in system, less damping

 © 2000 Mark Huckvale University College London