User manual
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Figure 2.10. FGEN Output Enabled
5. Measure the voltage by connecting the positive probe to the positive lead of resistor R1 and the negative probe
to the negative lead of resistor R10 (refer to Figure 2.5 for connections). This measures the voltage drop across
the entire circuit. Record your measured voltage in the field below.
a. Total DC Voltage Drop (measured):_______________________
6. After taking the voltage measurement, turn off the FGEN by pressing the power button to disable the output.
Exercise 2.3: Measuring AC Voltage
In the previous exercise, you measured a DC (direct current) signal. These signals are relatively stable and unchanging
with respect to time. You do not need to use any special techniques to measure them.
Comparatively, an AC (alternating current) signal does periodically oscillate over time. Since AC signals vary over time, it
is more useful to talk about average voltage measurements and power levels.
If you tried to take a regular average of an AC signal, you notice that no matter how you change the amplitude, you
always see a measurement close to 0 V. This happens because, as mentioned above, an AC signal alternates periodically
over time and any measurement that averages over time cancels out.
To take a proper voltage reading of an AC signal, an averaging method known as the root mean square (or RMS) value is
commonly used. In electrical engineering, the RMS value of a periodic current can be considered as the DC voltage that
delivers the same average power to a resistor as the periodic current. Now, consider a periodic sine wave of the form:
where a represents the amplitude and f represents the frequency of the sine wave. The RMS value is then given by the
equation below:
again, where a is the amplitude of the sine wave. Now repeat the measurements you made earlier with RMS
measurements and an AC signal.