PHY 114
Ohm’s Law
Cydni Scott
Partners: Daniela Alcazar, Charles Stocks
Section 12067
TA: Omer Faruk Albayrak
February 28, 2017
Abstract
For this experiment, we had to determine the resistance of a resistor from an I – V graph,
determine the resistivity of a graphite rod, and to determine the load resistance value at which
power is optimized in a DC circuit. The theoretical resistance of the carbon resistor used was
found to be 276.8Ω and this was found using a digital multimeter (DMM) and the experimental
data was found to be 321.4Ω by using the slope from an I – V graph that we plotted. From these
values, the percent error was calculated to be 13.9%. The resistivity of the graphite rod was
calculated to be 6.73 • 10
-6
. The load resistance value at which power is optimized in a DC circuit
was found to be 100Ω by using the P vs R
L
graph that we plotted. Then the power efficiency was
calculated to be 50.

Experimental Data
Part 1a: Current—voltage (
I – V
) characteristic for a carbon resistor
Table 1: Carbon resistor’s resistance value
Resistance value from color code
331Ω +/- 5%
Resistance value from DMM
276.8
Table 2: (
I – V
) data range
Volts (V)
Current (A)
Resistance (Ω)
1.135
0.003
378.3
3.04
0.009
337.8
5.05
0.015
336.7
7.06
0.021
336.2
9.01
0.027
333.7
12.09
0.037
326.8
15.25
0.047
324.5
Graph 1: