Equipment Accuracy: Explaining Micro-Amp & CRO Results

[dagg3r]

hi all, can someone explain to me if i were to theoretically calculate current using an ammeter in small units eg micro amp's 10^-6 and physically use an ammeter to obtain results why do they differ greatly?

and also when i am using a cathode ray oscilloscope (CRO), when i am measuring voltage peak-peak values what equipment\limitations\techniques are causing the results to differ greatly then the theoretical results.

 

[Ouabache]

You may be encountering a small internal impedance, inherent in your power supply and also the ammeter, that can cause your readings to vary from theoretical values. If your are finding large variations in your measured values from theoretical.. You may be loading your circuit. You can read more about accuracy and meter loading at this http://www.elexp.com/t_elec.htm (see parts 1 and 2).

hi all, can someone explain to me if i were to theoretically calculate current using an ammeter in small units eg micro amp's 10^-6 and physically use an ammeter to obtain results why do they differ greatly?

For the scope, there is a certain amount of error inherent in the instrument at each setting. Look at the scope manual and find its accuracy measured in percent, at various settings.. Using probes (designed to work with your scope) will also effect accuracy.
There are different http://www.optics.arizona.edu/Palmer/OPTI380B/lablec05.pdf (and settings) for different conditions. Passive probes are the most common and a 10x setting tends to improve accuracy but also attenuates the voltage of signal you're measuring. Besides passive, there are also active and current probes. Each used for different applications. Using the wrong probe, will certainly impact accuracy of your measurement.

Also when i am using a cathode ray oscilloscope (CRO), when i am measuring voltage peak-peak values what equipment\limitations\techniques are causing the results to differ greatly then the theoretical results.

 

[ravenprp]

There are a few factors that can contribute to differences between theoretical and actual results when using equipment to measure small units like micro-amps or peak-peak voltage values.

Firstly, equipment accuracy is a major factor. Even the most precise ammeters and CROs have a margin of error, which can be affected by factors such as temperature, age, and calibration. This means that the readings obtained from the equipment may not be exactly the same as the theoretical values.

Additionally, there may be limitations or techniques involved in using the equipment that can affect the results. For example, when using an ammeter, the resistance of the circuit being measured can impact the accuracy of the reading. If the resistance is high, it can cause a voltage drop and affect the current measurement. Similarly, when using a CRO, the impedance of the probe and the circuit being measured can affect the accuracy of the voltage readings.

Another factor to consider is human error. When physically using equipment, there is always a possibility of human error in reading the measurements or setting up the equipment correctly. This can also contribute to differences in results.

In summary, equipment accuracy, limitations or techniques, and human error can all play a role in causing differences between theoretical and actual results when using equipment to measure small units like micro-amps and peak-peak voltage values. It is important to carefully consider these factors and take necessary precautions to minimize errors and obtain accurate results.