Ohm's Law Physics Lab #20
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Introduction
Ohm’s Law
Physics Lab #20
Name: Diana Abou Hassan
Partners: Sara Jaber
Michael Muhanna
Rami Jachi
Date Performed: 14/11/2002
Date Due: 21/11/2002
Teacher: Mrs. Khoury Saab
Objective:
The objective of this lab is to determine the relationship between the potential difference across a conductor and the electric current through it. \
Materials:
- Low voltage variable DC power supply\
- Two different resistors
- 2 digital multimeters
- connecting wires
Procedure: Please refer to lab sheet.
Data Collected:
Resistor 2
Voltage (V) | 1 | 1.5 | 2 | 2.5 | 3 | 3.5 |
Current (mA + 0.01mA) | 0.42 | 0.72 | 1.16 | 1.56 | 1.91 | 2.30 |
Potential Difference (V + 0.001V) | 0.526 | 0.877 | 1.404 | 1.893 | 2.324 | 2.796 |
Middle
2.359
2.793
Resistor 2 = 1.202 KΩ
Resistor 7 = 5.07 KΩ
Light Bulb
Before lighting up:
Voltage (V+ 0.0001V) | 0.0069 | 0.0781 | 0.5780 | 0.6560 | 0.7590 |
Current (mA+ 0.01mA) | 0.90 | 10.50 | 81.30 | 92.40 | 109.70 |
The light bulb lit up at:
Voltage (V+ 0.0001V) | 1.0010 |
Current (mA+ 0.01mA) | 149.30 |
After lighting up:
Voltage (V+ 0.0001V) | 1.6090 | 1.8310 | 2.116 |
Current (mA + 0.01mA) | 182.30 | 200.00 | 223.50 |
Data Analysis:
Calculate the slope of each graph:
Sample Calculation:
Slope of Resistor 2 = (y2 – y1) / (x2 – x1)
= (2.30 V – 0.42V )/(2.796mA – 0.526mA)
= (2.30 V – 0.42V )/(0.
Conclusion
Sources of Error:
The manual adjustment of the voltage may have caused some error as we may have not adjusted it to the exact values required. If there were a more detailed and precise knob, it could reduce the error. Also, the wire were very rusty therefore acting as very poor conductors. The obvious solution would be to use newer wires.
Conclusion:
The purpose of this lab was to see how the potential difference and the electric current going through a conductor are related. By graphing the results it showed that they were directly proportional. This proved to be correct also for the cold resistivity of the light bulb, however the resistivity of the light bulb after it lit up contradicted Ohm’s law as the resistivity did not remain constant.
This student written piece of work is one of many that can be found in our AS and A Level Electrical & Thermal Physics section.
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