Figure 1 depicts the set up of the circuit.[1]
Figure 2 depicts the set up for measuring the theoretical resistance for the carbon resistor.[1]
Section 3: Results and Discussion
Data and Graphical Representation
Voltage (V)
Current (mA)
0
0
1.01
2.9
1.99
5.6
3.01
8.5
4.01
11.4
R
load
ammeter
5.01
14.3
5.99
17
7
19.9
8.01
22.8
9.01
25.6
9.99
28.4
Figure 3 depicts the data recorded for the measurement of the decade box.
0
2
4
6
8
10
12
0
2
4
6
8
10
12
f(x) =
R² = 0
Current(mA) v. Voltage(V)
Voltage (V)
Current(mA)
Slope of Best Fit Line: 2.8436X10
-3
A
V
Experimental Resistance (from slope), R
exp
: 351.67
Ω
Linear Correlation coefficient squared, r
2
: 1
Decade Box setting: 350
Ω
Percent Error in Resistance: .48%
Figure 4 depicts the date in Figure 3 in graphical form
Voltage (mA)
Current (V)
0
0
1
2.1
1.99
4.2
3.01
6.4
4
8.6
5.01
10.7
6
12.9
7.01
15
8.01
17.2
9
19.3
10
21.5
Figure 5 depicts the data measured and recorded for the Carbon Resistor
0
2
4
6
8
10
12
0
5
10
15
20
25
f(x) = 2.15x - 0.05
R² = 1
Current vs Voltage
Voltage (V)
Curremt (mA)
Color Bands of Resistor: yellow, violet, brown, gold
Nominal Resistance: 470Ω ± 5% of 470Ω
Slope of Best Fit Line: 2.1515 X 10
-3
A
V
Linear correlation coefficient squared, r
2
: 1
Experimental Resistance (from slope), R
exp
: 465k Ω
Theoretical Restistance (from ohmmeter), R
theo
: 464kΩ
Percent Error in Resistance: .2%
Figure 6 depicts the data in Figure 5 in graphical form
Voltage(V)
Current (mA)
0
0
0.1
17.9
0.2
34.7
0.31
48.5
0.4
60.6
0.5
79.4
0.6
89.9
0.7
96.9
0.8
104.4
0.9
110.5
1
119
1.1
132.2
1.2
137.6
1.3
144.4
1.4
151.4
1.51
156.8
1.6
162.6
1.7
168.2
1.8
173
1.9
178
2
181.6
2.09
186.8
2.2
190.4
2.31
197.5
2.4
198.3
Figure 7 depicts the data points measured and recorded for the lightbulb.
0
0.5
1
1.5
2
2.5
3
0
50
100
150
200
250
f(x) = 77.86x + 31.33
R² = 0.95
Current (mA) vs Voltage (V)
Voltage (V)
Current (mA)
Linear Correlation coefficient squared r
2
: .953
Figure 8 depicts the graphical representation of Figure 7. Notice how the data is of this
lightbulb graph is not straight as the others, this is due to it being a non-ohmic device.
Data Analysis
The data above shows the voltage and the current for the 3 types of resistors:
dedicator box, carbon resistor and a lightbulb. First the resistor was hooked up to the power
supply as show in figure 2. Then the output voltage on the power supply was increased by a
factor of 1 volt each time the readings were measured. The nominal resistance was calculated
by looking at the color of the resistor bands and determining the value based on the colors. In
order to read the resistance, the first two numbers are put together but not added and the third
number is the number of zeros tacked on the end of the number and the last color is read as
the tolerance which gives a range and not an exact number. The colors were yellow, violet,
brown and gold which respectively correspond to 4, 7, 1, and 5%; thus, the resistance read is
470
Ω
± 5% of 470.
The repetition of the experiment was done to acquire the necessary data
to construct a table of value and plot the graphs seen above. The slope that was obtained from
the graphs is defined in this experiment as current divided by voltage although in the equation
for resistance voltage is divided by current so to get the resistance of the devices 1 was
