# phy lab

Topics: Resistor, Electrical resistance, Power supply Pages: 7 (405 words) Published: October 30, 2013
﻿EC1
VI-1 The results of experiment EC1 part V1 are summarized as below. V, I, Rm are directly measured

Resistor A
Resistor B
Resistor C
Resistor D
V±ΔV(V)
6.748±0.001
7.759±0.001
9.061±0.001
10.383±0.001
I±ΔI(mA)
44±0.5
35±0.5
23±0.5
10±0.5
V/I±ΔR(Ω)
153.36±1.7
221.69±3.2
393.96±8.61
1038.30±52.02
Rm±ΔRm(Ω)
145.21±0.01
214.90±0.01
385.60±0.01
907.50±0.01

VI-2
(V, I) pairs for Resistor A using a DC power supply
V-2 f = 0 Hz

#
V(Volts)
I(mA)
1
1.994
13
2
3.807
25
3
4.920
32
4
6.653
44
5
7.436
49

(V, I) pairs for Resistor A using a AC power supply, frequency f=1000Hz, R1 = 145.21Ω V-5(1) f = 1k Hz

#
Vpp(Divisions)
V1pp(Divisions)
Volts/Div
I = V1pp/R1(mA)
1
5.2
7.2
1
49.583
2
1.4
2.0
1
13.773
3
2.8
4.0
1
27.546
4
3.8
5.0
1
34.433
5
4.2
6.0
1
41.319

(V, I) pairs for Resistor A using a AC power supply, frequency f=10000Hz, R1=200Ω V-5(2) f = 10k Hz

#
Vpp(Divisions)
V1pp(Divisions)
Volts/Div
I = V1pp/R1(mA)
1
5.2
7.2
1
49.583
2
1.4
2
1
13.773
3
2.9
4
1
27.546
4
3.4
5
1
34.433
5
4.2
6
1
41.319

The V vs. I graphs of the above 3 tables are plotted below. The trend lines and their equations are also calculated by EXCEL
From the graph above, we can see that the trend lines at frequencies 1kHZ and 10kHz coincides. but that of 0Hz show a different resistance. I think we make a mistake here. We use resistor D for V2 but resistor A for V5. Using the LINEST function of EXCEL:

For DC
S(kΩ)
0.150769139
0.046926058
I(V)
σS (kΩ)
0.001155998
0.040558901
σI (V)

For frequency f=1000Hz
S(kΩ)
0.14521
8.88178E-16
I(V)
σS (kΩ)
8.21861E-18
2.9173E-16
σI (V)

For frequency f=10000Hz
S(kΩ)
0.14521
8.88178E-16
I(V)
σS (kΩ)
8.21861E-18
2.9173E-16
σI (V)

(V,I)pairs for a Slicon diode using a DC power supply
#
V (V)
I (mA)
1
0.20
0
2
0.40
0
3
0.60
1
4
0.65
5
5
0.70
17
6
0.71
21
7
0.72
26
8
0.73
31
9
0.74
39
10
0.75
49

The V vs. I graph of the silicon diode is plotted using EXCEL

R0.60 = 0.60 / (1×10-3) = 600 Ω
R0.65 = 0.65 / (5×10-3) = 130 Ω
R0.70 = 0.70 / (17×10-3) = 41Ω

The diode is not an Ohmic device because the graph of its V vs. I is not a straight line. VI-3
For resistors in series
Expect Req= RA+RB+RC+RD
= 145.21+214.9+385.6+907.5 Ω
= 1653.21 Ω
σReq=σRA +σRB +σRC +σRD =0.01+0.01+0.01+0.01=0.04Ω

Calculated Rcalc= 5.662/(3x10-3) = 1887.3 Ω
=315Ω
Measured Rm=1492±1Ω

The measured and the expected resistances Rm and Req are included in the range of calculated resistance. VI-4 For resistors in parallel
Expect
Req=65.64Ω
σReq=σRA +σRB +σRC +σRD =0.01+0.01+0.01+0.01=0.04 Ω

Calculated Rcalc=2.363/(34 x10-3)= 69.5Ω
=1.022 Ω

Measured Rm=66.33±0.01Ω

By comparing the reported values above, Req, Rcalc and Rm overlap each other.