Question

How to calculate resistivity with the given date?

Lab 3: Resistance and Resistivity Cross Sectional Measured Accepted Relative Do the measured resistivities agree Material Color Yellow Diameter (cm) 0.127 0.102 0.102 0.102 0.102 Area A (cm") Current (A) Slope (mV/cm) Resistivity (μΩcm) Resistivity (μΩcm) Difference with the accepted resistivities? Brass Aluminum Light Gray Copper Nichrome Stainless Steel Dark Gray 0.016129 0.010404 0.010404 0.010404 0.010404 1 1.49 t 0.016 1 0.700 +0.0083 1 0.223 10.0034 0.5 7.23 0.0039 1 10.3t0.025 7.0t0.5 4.9 0.1 1.8 +0.1 105+5 Reddish Dark Gray

Answer 1

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We know: Resistance (R) = delta l/A rightdoublearrow delta = R A/l rightarrow For calculate delta, we need R, A & l (1) A is given in data (2) v/l (mv/cm) is given in data and Current (I) is given so(v/l)/I = (V/I) middot 1/l = (R/l) for brass: A = 0.016129 cm^2 = 0.016129 times 10^-4 m^2 R/l = V/l/I = 1.049/1 times 10^-3/10^-2 V/m A(R/l) = A (V/l)/I = 0.0016/1 R/l = 0.149 l/m therefore delta = R A/l = 0.149 times 0.016129 times 10^-4 delta = 24.03 times 10^-8 ohm - m = 24.03 mu oh - cm therefore delta = 24.03 plusminus 0.25 mu ohm - cv that for every specimen, we can calculate delta delta/delta = delta (R/l)(R/l) = 0.016 times 10^-3/10^-2 ohm/m/0.149 delta delta = 0.0016/0.149 times 24.03 mu ohm cm = 0.25 mu ohm - cm

Use this method and calculate for other specimens