Which is the major source of random error, measurement of voltage or mesurement of current?

Question

n a physics experiment i measured voltage using a digital voltmeter and current using an ammeter so that i could calculate a resistor's resistance and i would like to know what is the major source of error, either voltage or current. your help would highly be appreciated!!!!

Answer 1

Your experiment and most of of real life circuits more likely use constant-voltage excitation. The external control maintains a constant voltage supply by letting the current float freely. With no biased knowledge of the internal working of the DMM, the measurement of current, hence, is more likely to display a larger variance of random error.

Component switching inductive kicks, thermistor-like heating effects, crosstalk noise, thermal noise, etc..., for example, all contribute to current ripples. The voltage also wants to ripple as much but is pinched down and filtered by the source's constant-voltage control (i.e. a row of large to small caps in the power supply to overrule all ripple frequencies, and a control loop to maintain a fixed average voltage level).

Current measurement, in addition, is likely more disturbing to the experiment circuit due to the insertion of either a small series load which reduces the current, or an inductive-coupling coil which induces a counter current; both probing methods disrupt the characteristics of the test circuit. Voltage measurement, on the other hand, more likely loads down the external supply by a very large resistor, and hence with relatively less disruption to the characteristics of the test circuit.

If you used a constant-current supply the analysis would reverse.

Answer 2

Measurement Of Voltage And Current

Answer 3

The major source of error is neither the voltage or the current. The major source of error is the resistor you are measuring. A good volt and current meter has about a + or - 0.1% error, but the resistor has a color band (or not) that indicates the resistor's % of error. (The 4th band)

20% error = (no color band)
10% error = Silver
5% error = Gold
2% error = Red
1% error = Brown

So even with a theoretically perfect voltage and current meter, the resistor itself has a much higher % of error. Which in-turn, is the major source of error.

Answer 4

As voltage and current are related, random fluctuations in one would be mirrored by random fluctuations in the other. My guess, as a trained EE student with a physics degree, is that the precision and accuracy of the measuring devices, and the skills of the measurer will have more bearing on random errors than any random fluxes in either voltage or current.

Very good question, sorry I don't have a more definitive answer. But I've never run across any studies that have examined this issue.

Answer 5

The main cause of error is probably the meters affecting the circuit especially the ammeter that have a resistance higher than the ideal of zero. The voltmeter will have a resistance lower than the ideal of infinity

Answer 6

offered the circuit involves purely linear, passive aspects and any source impedance is likewise linear or might want to correctly be neglected, then the present will also triple. If we assume of in words of authentic aspects (somewhat than linear) then resistances are many times temperature depending, their resistance customarily increasing as temperature rises. for this reason truly the present might want to correctly no longer fairly triple because the resistances are operating hotter.

Answer 7

Need more info to answer this question. What is the manufacturer and model numbers of the meters used. What is the resolution and accuracy of the meters. this will have alot of influence on the total uncertainty.