Question

Help determining R and uncertainty , data and question posted below

Tabulate the data from V-1 including the following: For each unknown resistor, tabulate lı, l2, Rz and Rm Determine and report R, Orx for all four resistors Compare the resistance determined from the Wheatstone bridge to the resistance using the DMM. Compare the values determined by using an AC power source to those determined by using a DC power source.

This was all info i was given

Answer 1

From the given data we can see, we are gievn
Resistor names,
for each resistor we are given length l1, l2, R3 and Rm
now for a wheatstone bridge
l1/l2 = R3/Rm

So from the below filled table we can see that l1/l2 and R3/Rm qare not seperated a lot in terms of percent difference

Below is the completely filled table with values of l1/l2 and R3/Rm as well as percent difference between the both

Resistor	l1 (cm)	l2 (cm)	R3	Rm	l1/l2	R3/Rm	% diff
A	50.1	49.9	148	147.7	1.004008	1.002031	0.197286
B	50	50	215	215	1	1	0
C	50	50	386	285.7	1	1.351068	-25.9845
D	50.1	49.9	982	980.1	1.004008	1.001939	0.206543

now,
Rm = R3*l2/l1
dRm/Rm = dR3/R3 + dl2/l2 + dl1/l1
now, dl1 = dl2 = 0.1 cm
also, dR3 = 0.1 ohm
hence
for all the resistors, we get value of dRm, the filled table is as under

Resistor	l1 (cm)	l2 (cm)	R3	Rm	l1/l2	R3/Rm	% diff	dRm/Rm	dRm	Rm
A	50.1	49.9	148	147.7	1.004008	1.002031	0.197286	0.004676	0.6906	147.7 +- 0.6906
B	50	50	215	215	1	1	0	0.004465	0.96	215+-0.96
C	50	50	386	285.7	1	1.351068	-25.9845	0.004259	1.216816	285.7+-1.21681
D	50.1	49.9	982	980.1	1.004008	1.001939	0.206543	0.004102	4.020222	980.1 +- 4.02022

The last column has resistance Rm with uncertinaity
hence for A, Rm = 147.7 +- 0.6906 ohm
for B, Rm = 215+-0.96 ohm
for C, Rm = 285.7+-1.21681 ohm
for D, Rm = 980.1 +- 4.02022 ohm