I-v
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Name : Adam Okoe Mould Title : Charles Law Criteria : DCP, CE Aim : To investigate the I-V characteristics of a lamp and resistor Raw Data Lamp Voltage / V ± 0.01V 1.85 2.1 2.35 2.52 2.88 3.11 3.53 3.77 4.03 4.50 4.53
Current / A ± 0.01A 0.36 0.40 0.44 0.47 0.50 0.52 0.55 0.61 0.64 0.67 0.69
Resistor Voltage / V ± 0.01V 1.63 2.10 2.76 3.01 3.33 3.92 4.34
Current / A ± 0.01A 0.48/0.44 0.56 0.74 0.81 0.9 1.05 1.17
Observations As the current increased, the lamp became brighter and brighter and also became warmer and warmer. For both the resistor and lamp, as current increased voltage increased.
Analysis of ohmic and non-ohmic characteristics
4.5
y
Graph of Voltage against Current for the lamp and resistor
Lamp
Resistor
4 3.5 3 2.5 2 1.5
e/ g lta o V 1 0.5 x -0.1
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Current / A
0.8
0.9
1
1.1
1.2
Comment on Graph and Processed Results For both the resistor and the current the lines of best fit were upward sloping indicating that as voltage increased, current increased For the resistor; A straight line almost passing through the origin is observed. The gradient is constant. This indicated that the resistance is constant. Hence, the resistor is an ohmic conductor. For the lamp; An upward sloping curve is observed. The gradient of the slope becomes steeper and steeper as the current increases. This indicated that the resistance becomes greater and greater as the current increases. Hence, the lamp is a non-ohmic conductor.
Conclusion For the resistor, as the graph of voltage against current showed a line of best fit with a constant gradient, it indicated that the resistance was constant. Therefore, the resistor exhibited ohmic characteristics. For the lamp, as the graph of voltage against current showed a line of best fit with an increasing gradient, it indicated that the resistance was constant. Therefore, the resistor exhibited non-ohmic characteristics. Sources of Error 1. The circuit was used for a long time. Hence heat could have generated in the conducting wires causing the resistance to increase and the voltage measured to decrease Improvements to the Investigation 1. For each conductor, i.e. the lamp and the resistor use a different set of wires so that the error of heated wires will be minimized. Also the experiment could be carried out quickly to minimize the extent to which the wires heat up.
Current / A ± 0.01A 0.36 0.40 0.44 0.47 0.50 0.52 0.55 0.61 0.64 0.67 0.69
Resistor Voltage / V ± 0.01V 1.63 2.10 2.76 3.01 3.33 3.92 4.34
Current / A ± 0.01A 0.48/0.44 0.56 0.74 0.81 0.9 1.05 1.17
Observations As the current increased, the lamp became brighter and brighter and also became warmer and warmer. For both the resistor and lamp, as current increased voltage increased.
Analysis of ohmic and non-ohmic characteristics
4.5
y
Graph of Voltage against Current for the lamp and resistor
Lamp
Resistor
4 3.5 3 2.5 2 1.5
e/ g lta o V 1 0.5 x -0.1
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Current / A
0.8
0.9
1
1.1
1.2
Comment on Graph and Processed Results For both the resistor and the current the lines of best fit were upward sloping indicating that as voltage increased, current increased For the resistor; A straight line almost passing through the origin is observed. The gradient is constant. This indicated that the resistance is constant. Hence, the resistor is an ohmic conductor. For the lamp; An upward sloping curve is observed. The gradient of the slope becomes steeper and steeper as the current increases. This indicated that the resistance becomes greater and greater as the current increases. Hence, the lamp is a non-ohmic conductor.
Conclusion For the resistor, as the graph of voltage against current showed a line of best fit with a constant gradient, it indicated that the resistance was constant. Therefore, the resistor exhibited ohmic characteristics. For the lamp, as the graph of voltage against current showed a line of best fit with an increasing gradient, it indicated that the resistance was constant. Therefore, the resistor exhibited non-ohmic characteristics. Sources of Error 1. The circuit was used for a long time. Hence heat could have generated in the conducting wires causing the resistance to increase and the voltage measured to decrease Improvements to the Investigation 1. For each conductor, i.e. the lamp and the resistor use a different set of wires so that the error of heated wires will be minimized. Also the experiment could be carried out quickly to minimize the extent to which the wires heat up.
