In a laboratory investigation

PHYSICS · Multi-part · CBSE · Physics · Current Electricity · Current Electricity

Problem

In a laboratory investigation, three digital ammeters are connected to measure the currents at a single junction K in a complex network of resistors. Ammeter A records the current entering the junction; ammeters B and C record the currents leaving along two separate branches. The instruments report the following time-averaged values (already corrected for zero offset): Current entering:

I_{A}=0.48\,\text{A}\pm0.02\,\text{A}

Currents leaving:

I_{B}=0.30\,\text{A}\pm0.01\,\text{A}

and

I_{C}=0.18\,\text{A}\pm0.01\,\text{A}

Answer the questions below, showing all reasoning. (a) Determine the combined value

I_{B}+I_{C}

and its uncertainty, clearly indicating the method you use to propagate uncertainties. (b) Decide whether the experimental data support the claim that charge is conserved at junction K within the stated uncertainties. Justify your answer quantitatively. (c) If the data do not support conservation, propose one plausible experimental factor that could have produced the discrepancy and explain its effect on the measured values.

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