Sample lab report 7 - Prof Mark V. Brown and Stefan Kaluzienski Lab Section PDF

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Prof Mark V. Brown and Stefan Kaluzienski
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The following is a sample formal lab report. Anything in this report which is type in red will be provided for you in the formal report. Everything else which is type in black is information you must provide. This information can be either typed or written in ink.

Remember; when you are adding any pages to the report, you must number the pages with the number from the previous lab report page followed by a letter (see the sample calculation, results section where graphs which were added to this report and the error analysis section).

Mickey Louse Experiment #7 Your lab session Donald Luck Group 333 March 5th, 2001

Introduction Experiment # 7 Page 1 What is current? Current is the amount of charge passing a point over a period of time. What is Resistance? Resistance is an object which reduces or impedes the flow of current in a wire or an electrical component. What is voltage? Voltage is potential or emf defined as a product of current and resistance. How does resistance vary with temperature? In metals, as temperature increases the resistance will decreases. In semi-conductors, as temperature increases resistance will also increases.

Purpose: to determine the resistance and its relationship with temperature for a metal filament lamp and a carbon filament lamp.

Apparatus: Apparatus Power supply Voltmeter Ammeter Metal filament lamp Carbon filament lamp Lamp socket

Serial/Model Number 8704553 0606-635 0606-060 N/A

Uncertainty . ±0.5 v ±0.5 v ±0.5 mA N/A

N/A

N/A

N/A

N/A

Procedure:  Setup circuit as shown in diagram and install the carbon filament lamp  Set power supply to 0v  Increase voltage in steps of one volts up to 15v,record the current at each step  At each step record the scale used to measure the voltage and current  Repeat with metal filament lamp.

2

Drawing:

Sample Calculations: Carbon Filament Resistance R=

V I

R – Resistance in Ω V – Voltage in V I – Current in A

R=

1.00 V =215 Ω −3 4.65 x 10 A 3

Metal Filament Resistance R=

V I

R – Resistance in Ω V – Voltage in V I – Current in A

R=

1.00 V =25 Ω −3 40.0 x 10 A

3a

Results:

Data Table Voltage (V) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Scale (V) 1 1 2.5 5 5 5 10 10 10 10 10 25 25 25 25 25

Carbon Filament Current (mA) Scale (mA) 0 1 4.65 5 9.20 10 13.5 25 17.5 50 22.5 50 27.0 50 32.5 50 36.5 50 41.5 50 47.0 50 50.5 100 56.0 100 61.5 100 67.0 100 72.0 100

4

Metal Filament Current (mA) Scale (mA) 0 1 40.0 50 58.0 100 71.0 100 84.0 100 92.0 100 97.5 100 103 250 108 250 110 250 115 250 118 250 120 250 125 250 128 250 130 250

Results Table

Voltage (V) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Carbon Filament Current (mA) Resistance (Ω) 0 undefined 4.65 215 9.20 217 13.5 222 17.5 229 22.5 222 27.0 222 32.5 219 36.5 219 41.5 217 47.0 213 50.5 218 56.0 214 61.5 211 67.0 209 72.0 208

5

Metal Filament Current (mA) Resistance (Ω) 0 undefined 40.0 25.0 58.0 34.5 71.0 42.3 84.0 47.6 92.0 54.3 97.5 61.5 103 68.3 108 74.4 110 81.8 115 87.0 118 93.6 120 100 125 104 128 109.8 130 115.4

Voltage vs Current Carbon Filament 16 f(x) = 0.21 x + 0.25 14

12

Voltage (mA)

10

8

6

4

2

0 0

10

20

30

40 Current (mA)

5b

50

60

70

80

Voltage vs Current Metal Filament 16

14

12

Voltage (V)

10

8

6

4

2

0 20

40

60

80 Current (mA)

5b

100

120

140

.

5c

Resitance vs Current for Carbon Filament 250

f(x) = − 0.19 x + 223.94

Resistance (ohms)

200

150

100

50

0 0

10

20

30

40 Current (mA)

5c

50

60

70

80

Error analysis: Error calculations: For 1 volt step ∆ I =scale∗accuracy=5 mA∗.02= 0.1 mA=.0001 A

For 7 volt step ∆ I =scale∗accuracy=50 mA∗.02=1.0 mA =.001 A

For 15 volt step ∆ I =scale∗accuracy=100 mA∗.02=2.0 mA=.002 A

Calculation of Resistance uncertainty For 1 volt step ∆ R ∆ V ∆ I .02 V .0001 A =.041 + = + = 1 V .00465 A I V R ∆ R=R∗.041 =215 Ω∗.041=±8.9 Ω

For 7 volt step ∆ R ∆ V ∆ I .2 V .001 A =.059 = + = + R V I 7 V .0325 A ∆ R=R∗.059 =219 Ω∗.059=±12.9 Ω

6

For 15 volt step ∆ R ∆ V ∆ I .5 V .002 A =.061 + = + = 15 V .072 A I V R ∆ R=R∗.061 =208 Ω∗.061=±12.7 Ω

6a

Error analysis (cont.): Possible sources of errors for this experiment are:

Sources errors in this experiment came from the uncertainty of the meters and the parallax of reading the meter. Other sources of errors were assuming that the meters consumed no power when in fact some current was lost operating the meter.

Conclusion: The voltage vs current graphs for both filaments decreased with voltage as expected. The resistance vs current graph for the metal filament showed that as current increased the resistance decreases and the resistance vs current graph for the carbon filament showed that the resistance increases as current increases.

7

EXPERIMENT # 7 RESISTANCE MEASUREMENT WITH AMMETER AND VOLTMETER Equipment, serial numbers and uncertainties: voltmeter voltmeter 0606-635 0606-635 ±.5V ±.5V Power supply 8704553 ±.5V ammeter 0606-060±.5mA

Voltage

Scale

Carbon Current (mA) Scale Scale (mA) (mA)

Metal Scale (mA) Current (mA)

1

1

4.65

5

40.0

50

2

2.5

9.20

10

58.0

100

3

5

13.5

25

71.0

100

4

5

17.5

50

84.0

100

5

5

22.5

50

92.0

100

6

10

27.0

50

97.5

100

7

10

32.5

50

103

250

8

10

36.5

50

108

250

9

10

41.5

50

110

250

10

10

47.0

50

115

250

11

25

50.5

100

118

250

12

25

56.0

100

120

250

13

25

61.5

100

125

250

14

25

67.0

100

128

250

15

25

72.0

100

130

250

Name: Partner's Name: Date: TA's Signature...