3 The machine always produces a small amount of DC current in the readings

# 3 the machine always produces a small amount of dc

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3. The machine always produces a small amount of DC current in the readings which is negligible when the frequency is high enough. By looking at eq 1.1, we can observe that as the frequency approaches the limit of zero, the AC voltage component Vac (sin(2pi*f*t)) approaches zero. Thus, for the 1Hz signal, the dominant voltage component is Vdc (independent of frequency). Contrarily, for high
frequencies, Vdc is negligible compared to Vac, as we experimentally observed . There is barely any difference between the Vpp and Vdc for high frequencies waves. On AC coupling mode, the DC systematic errors made by the function generator are filtered and removed. The DMM value can not always be relied upon as it keeps making random errors for some frequencies. Therefore, as far as accuracy is concerned, the AC coupling mode is a better option. Also, the AC filter efficiency depends on the voltage frequency. 4. The DMM operates on a fixed rate of sampling. It collects many discrete samples over a fixed amount of time. In the case of the 1 Hz sine wave, the value of V rms is not accurate because the period of the function is too long (1s) in comparison to the rate of the fixed sampling of the DMM. The samples are very close to each other, thus do not represent many distinct sections of the waveform (invalid value). Due to this, the DMM cannot read the function completely so it makes mistakes and produces random values with extremely high error. In the case of the 2 MHz sine wave, the value of V rms is not accurate because the period of the function is too short (0.5µs) in comparison to the rate of the fixed sampling of the DMM. Since function has too many periods on a certain time interval, the DMM’s measuring rate is too slow for the function. It reads only small parts of the wave which are too far from each other for it to give accurate readings. CONCLUSION This experiment elucidates many facts and verifies our formulae successfully. Some salient features the experiment illustrated were as follows: 1. The differences between the AC and DC Voltages were well portrayed especially through output using the oscilloscope which gives analogue signals. 2. We were able to create a graph of the signal hence plotting the constantly changing AC Voltage output accurately in a graph. 3. Crucially portrayed how devices such as the oscilloscope and DMM measure varying signals. 4. Demonstrates how extreme frequencies impact the output voltage as displayed through these devices. 5. Tells us about the properties of oscilloscope that it outputs analogue signals in graphical form, while DMM outputs digital signals. Both these devices have limitations when they measure the output voltage over extremely low or high frequencies due to the mechanism they use to output results. 6. Clearly shows how AC Voltage is a function of time while DC Voltage has no parameter.

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