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Lab 3, Ohms Law II

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Ohms Law II Resistors in Series and Parallel

Sophia Jones

Lab Partner: Courtney Dennis

Physics 231, Section 6, Foerster

February 7, 2012

Due: February 14, 2012

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Purpose/Method: The measurements made in this experiment will be used to understand Ohms

Law, resistors connected in series and parallel, voltage measurements in DC circuits, total

resistance of resistors in series and parallel, and the use of ammeters, voltmeters, and ohmmeters.

Data Tables:

Initial Data for Resistors

Band #1 Value Band #2 Value Band #3 Value Band #4 Value Tolerance*

Resistor #1 Br 1 Gn 5 R 2 Gd 1500 0.05

Resistor #2 Br 1 Bk 0 R 2 S 1000 0.1

Resistor #3 Gr 5 Bl 6 Br 1 S 560 0.1

* Uncertainties for this data are noted in the Tolerance column. For example, Resistor #1 has a tolerance

or uncertainty of +/- 5% for future calculations.

Calculations:

Resistors in Parallel

Table 1

Ohmmeter Values Slope Values % Difference Inverse Slope

Resistor #1 R1= 1485 Ohms R1= 1490 Ohms 0.34% 0.0007

Resistor #2 R2= 999 Ohms R2= 997.3 Ohms 0.17% 0.001

Resistor #3 R3= 560 Ohms R3= 554.35 Ohms 1.01% 0.0018

Measured Parallel Resistors RT= 289 Ohms RT= 291.62 Ohms 0.91% 0.0034

Calculated Parallel Resistors RT= 289 Ohms RT= 287.54 Ohms 0.51% 0.0035

% Difference 0.00% 1.42% 2.86%

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Table 2

Resistor #1 Resistor #2 Resistor #3 Parallel Resistors

Voltage,V (Volts)

Current, I(Amperes)

Voltage,V (Volts)

Current, I(Amperes)

Voltage,V (Volts)

Current, I(Amperes)

Voltage,V (Volts)

Current, I(Amperes)

0 0 0 0 0 0 0 0

1 0.00067 1 0.00099 1 0.00176 1 0.00339

2 0.00134 2 0.00198 2 0.00353 2 0.00678

3 0.00201 3 0.00298 3 0.0053 3 0.01018

4 0.00268 4 0.00397 4 0.00707 4 0.01357

5 0.00335 5 0.00497 5 0.00884 5 0.01697

6 0.00402 6 0.00596 6 0.01061 6 0.0204

7 0.00469 7 0.00696 7 0.01239 7 0.0238

8 0.00536 8 0.00795 8 0.01417 8 0.0272

9 0.00603 9 0.00895 9 0.01596 9 0.0306

10 0.0067 10 0.00995 10 0.0178 10 0.034

11 0.00737 11 0.01096 11 0.01961 11 0.0375

12 0.00804 12 0.01196 12 0.0214 12 0.0409

13 0.00872 13 0.01297 13 0.0233 13 0.0443

14 0.00939 14 0.01399 14 0.0251 14 0.0478

15 0.01006 15 0.015 15 0.0269 15 0.0513

16 0.01073 16 0.01602 16 0.0288 16 0.0548

17 0.01141 17 0.01704 17 0.0306 17 0.0583

18 0.01208 18 0.01807 18 0.0325 18 0.0618

Table 3

Current 5 Volts 10 Volts 15 Volts

Total IT 0.01703 0.0341 0.0516

Resistor #1 I1 0.00335 0.0067 0.01006

Resistor #2 I2 0.00499 0.00998 0.01505

Resistor #3 I3 0.00892 0.01785 0.0269

Sum I1+I2+I3 0.01726 0.03453 0.05201

% Difference Total & Sum 1.35% 1.26% 0.79%

Table 4

Power Supply VT 15

Resistor #1 V1 14.21

Resistor #2 V2 14.22

Resistor #3 V3 14.22

Table 1: The total resistance, RT, was found using the equation

. The slope values

were determined by creating a chart of the Voltage, V, versus Current, I, and inserting a trend

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line with a displayed equation. The slope of that line is equivalent to the value of RT. The percent

difference was found by using the equation

.

Table 2: The current, I (Amperes), was found using the equation

.

Table 3: The percent difference was found by using the equation

.

Resistors in Series

Table 5

Ohmmeter values Slope Values % Difference Inverse Slope

Resistor #1 R1= 1485 Ohms R1= 1490 Ohms 0.34% 0.0007

Resistor #2 R2= 999 Ohms R2= 997.3 Ohms 0.17% 0.001

Resistor #3 R3= 560 Ohms R3= 554.35 Ohms 1.02% 0.0018

Measured Series Resistors RT= 3030 Ohms RT= 3052.5 Ohms 0.74% 0.0034

Calculated Series Resistors RT= 3044 Ohms RT= 3041.65 Ohms 0.08% 0.0035

% Difference 0.46% 0.36% 2.86%

Table 6

Resistor #1 Resistor #2 Resistor #3 Series Resistors

Voltage,

V (Volts)

Current, I

(Amperes)

Voltage,

V (Volts)

Current, I

(Amperes)

Voltage,

V (Volts)

Current, I

(Amperes)

Voltage,

V (Volts)

Current, I

(Amperes)

0 0 0 0 0 0 0 01 0.00067 1 0.00099 1 0.00176 1 0.00033

2 0.00134 2 0.00198 2 0.00353 2 0.00066

3 0.00201 3 0.00298 3 0.0053 3 0.00098

4 0.00268 4 0.00397 4 0.00707 4 0.00131

5 0.00335 5 0.00497 5 0.00884 5 0.00164

6 0.00402 6 0.00596 6 0.01061 6 0.00196

7 0.00469 7 0.00696 7 0.01239 7 0.00229

8 0.00536 8 0.00795 8 0.01417 8 0.00262

9 0.00603 9 0.00895 9 0.01596 9 0.00295

10 0.0067 10 0.00995 10 0.0178 10 0.00328

11 0.00737 11 0.01096 11 0.01961 11 0.0036

12 0.00804 12 0.01196 12 0.0214 12 0.0039313 0.00872 13 0.01297 13 0.0233 13 0.00426

14 0.00939 14 0.01399 14 0.0251 14 0.00459

15 0.01006 15 0.015 15 0.0269 15 0.00491

16 0.01073 16 0.01602 16 0.0288 16 0.00524

17 0.01141 17 0.01704 17 0.0306 17 0.00557

18 0.01208 18 0.01807 18 0.0325 18 0.0059

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Table 7

Resistors in Series

Voltage 5 Volts 10 Volts 15 Volts

Total VT 4.99 9.98 14.97

Resistor #1 V1 2.43 4.87 7.3

Resistor #2 V2 1.639 3.27 4.91

Resistor #3 V3 0.918 1.836 2.75

Sum V1+V2+V3 4.987 9.976 14.96

% Difference Total & Sum 0.06% 0.04% 0.07%

Table 7: The percent difference was found by using the equation

.

Table 8

Power Supply VT 4.99

Resistor #1 V1 2.43Resistor #2 V2 1.639

Resistor #3 V3 0.918

ALL ERRORS IN THESE CALCULATIONS CAN BE ACCOUNTED FOR BY THE

TOLERANCE IN EACH RESISTOR.

Graphs:

Resistors in Parallel

y = 1490.4x + 0.0069

y = 997.3x + 0.0416

y = 554.35x + 0.0825

y = 291.62x + 0.0427

y = 3052.5x - 0.0001

-2

0

2

4

6

8

10

12

14

16

18

20

0 0.02 0.04 0.06 0.08

Vol

tage(Volts)

Current (Amps)

Voltage vs. Current Resistor #1

Resistor #2

Resistor #3

Resistors in

Parallel

Series Resistors

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Resistors in Series

y = 0.0007x - 5E-06

y = 0.001x - 4E-05

y = 0.0018x - 0.0001

y = 0.0034x - 0.0001

-0.01

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0 5 10 15 20

Current(Amps)

Voltage (Volts)

Current vs. Voltage

Resistor #1

Resistor #2

Resistor #3

Parallel Resistors

y = 1490.4x + 0.0069

y = 997.3x + 0.0416

y = 554.35x + 0.0825

y = 3052.5x - 0.0001

-2

0

2

4

6

8

10

12

14

16

18

20

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035

Voltage(Vol

ts)

Current (Amps)

Voltage vs. Current

Resistor #1

Resistor #2

Resistor #3

SeriesResistors

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Conclusion:

In conclusion, this lab helped to develop a better understanding of how circuits work and is

controlled by Ohms law. By demonstrating different configurations of the resistors either in

parallel or in series, it showed the behavior of circuits and how its components react to minor

changes.

y = 0.0007x - 5E-06

y = 0.001x - 4E-05

y = 0.0018x - 0.0001

y = 0.0003x + 5E-08

-0.005

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0 5 10 15 20

Current(Amps)

Voltage (Volts)

Current vs. Voltage

Resistor #1

Resistor #2

Resistor #3

SeriesResistors