Solutions

Questions

1. Answer: They are used to check voltage signals.
2. Answer: An oscilloscope graphs voltage over time.
3. Answer: It means that the voltage has dropped below the designated trigger voltage.
4. Answer: The rising edge is the line connecting 0 V to the max volts for the binary on/off signal plot.
5. Answer: The high signal can be seen at the highest point of the plotted line.

Exercises

1. Answer:  Change the first sleep(499) to sleep(749) and the second sleep(499) to sleep(249).
2. Answer: It is necessary to allow enough time for the voltage to reach its highest level.
3. Answer. Change the Time/Div value to a lower setting so only one rise and fall is shown.
4. Answer. The plot function.
    

Project

Solution. Remember the Your Turn activity in Measure Blinking Light with a Voltmeter. Your measurements showed decreased voltage. The oscilloscope graph will show the same thing. More resistance resulted in less current. It turns out that the voltage will remain about the same.  The increase in resistance results in less current, which in turn results in less light.  The LED has (mostly) unchanging forward voltage, so the change in current is simply caused by more resistance.  The voltage drops remain about the same, but since there is more resistance, there is less current to get the same voltage across the resistor.