2. Set the frequency to 60 Hz and the waveform to a sine wave. Use voltmeter to measure the voltage from the signal generator. Then measure the amplitude on the oscilliscope, using the vertical scale sensitivity. Compare the two numbers. Remember that the scope displays peak-to-peak voltage and voltmeter reads root mean square (rms) voltage. See your textbook for the relation between the two. The voltage amplitude is one-half the peak-to-peak voltage.
3. Lissajous figures: When two simple harmonic motions at right angles combine, the pattern is in general very complex. However, if the frequencies are in the ratio of small integers, then for certain phase relationships simple steady figures result. For example:
To produce Lissajous figures: Instead of using a sawtooth sweep which causes the trace to move horizontally at a constant velocity, switch the Time/cm selector to put the scope in the X-Y mode.
If we now apply a sine wave from the signal generator to the Y input, the scope will show the path traced out by a particle oscillating with simple harmonic motions in two perpendicular directions. This path is a Lissajous figure.
The frequency scale on the signal generator is only approximately correct, but the 60 Hz signal is a good frequency standard. An integer frequency ratio between the two frequencies will give a stationary Lissajous pattern. Observe and explain the patterns with frequency ratios 1:2, 1:3, 2:3, 1:1. Use Lissajous figures to calibrate your signal generator at 120 Hz and 300 Hz.