Ohm's Law

Ohm's Law

Introduction

Resistance is one of the properties of a wide range of materials that conduct electricity. Ohm's law uses a simple linear equation V=IR to relate the resistance of a material to the current flowing through it and the applied voltage. In this experiment resistive materials and Ohm's law are studied. In the first part of the experiment a 10-ohm (Ω) resistor is used and a scope of voltage vs current is developed, using the ratio of these two it is possible to calculate resistance. Furthermore, the same procedures are applied using a 100-ohm (Ω) resistor. Finally, a light bulb filament is used using the same procedures in order to observe the changes in resistance.

Experimental Procedure

Science workshop interface is connected to the computer. A 10-ohm (Ω) resistor is placed at the corner of the AC/DC electronic lab board, and the proper plugs and cords were connected. Afterwards, the data was measured and the curve was recorded. Furthermore, the same procedures were repeated using a 100-ohm (Ω) resistor.

The appropriate computer connections, and adjustments were applied. The resistor was removed from the component springs on the AC/DC electronics lab circuit board. Furthermore, two of the 10" leads were used to connect above and below 3VOLT BULB "C". In addition, the data was measured, and a scope display of voltage vs current was developed.

Results

After performing the procedures of the experiment, using the 10-ohm (Ω) resistor, a scope of voltage vs. current was developed. Furthermore, using the smart tool that shows the coordinates of a point on the trace of voltage versus current was used in order to determine the voltage and current for the 10-ohm (Ω) resistor. Using Ohm's law VR=IR and the obtained ratios of voltage vs. current, resistance could be found from the gradient of the graph.

Voltage (V) in V Current (I) in A Resistance (Ω)

2.669 0.262 10.18

0.646 0.063 10.25

2.582 0.260 9.93

Table 1- The obtained values of voltage and current and the calculated resistance, using a 10-ohm (Ω) resistor.

Calculating the average of the calculated values of resistance, the resistance obtained is 10.12 ohm. When comparing that value to the resistance of the resistor that was used, which is a 10-ohm (Ω) resistor, a percent error around 1.19% was calculated for each of the values, and it is noted that the resistance was relatively constant. Therefore the experiment was a success.

Furthermore, applying the same procedures when the 100-ohm (Ω) resistor is used, the following data was obtained, and the resistance was calculated.

Voltage (V) in V Current (I) in A Resistance (Ω)

1.385 0.014 99.00

0.270 2.688 x 10-3 100.44

1.878 0.019 99.00

Table 2- The obtained values of voltage and current and the calculated resistance, using a 100-ohm (Ω) resistor.

Calculating the average of the calculated values of resistance, the resistance obtained is 99.5ohm. When comparing that values to the resistance of the resistor that was used, which is a 100-ohm (Ω) resistor, a percent error of about 0.5% is calculated for each of the values, and it is noted that the experiment was a success. Furthermore, it was noted that the resistance was relatively constant.

After performing the appropriate