Measuring Electric Current
Here we connected a battery to power a light bulb via alligator clips. We see that all the components are functional and the bulb lights up.
We connected an ammeter to a position before and after the bulb as shown in the diagram below to measure the electric current at those positions. We found that the current was 110 +/- 5 mA for both positions. This means that the current remains constant.
Measuring Electric Potential, Current and Resistance
(Picture of the resistor used)
Our next set up was a bit different and consisted of a voltage supplier and a resistor shown in the picture below. An ammeter was again used to measure the current and a voltmeter was used to measure electric potential.
We plotted a graph showing the current vs voltage for the data that we obtained from our resistor and the data that our neighboring group obtained from their resistor. The two lines were plotted and fitted with linear trendlines which suggests that there is a linear relationship between current (I) and voltage (V), (they are proportional). We can say that I=kV, where k is a constant. We learned that solving for k (k=I/V), we get the resistance (R). So now we can say that I=RV. From our graph, the slopes of the trendlines are actually the resistance of the resistors. The two resistors were different and had a different resistance. This is shown by the slopes of the two lines, they are both different.
Other Variables
In this part of the experiment, we measured the resistance of 7 different wires with unique characteristics. They varied in material, length, and diameter. Plotting a graph of resistance vs length we get the curve shown above. The majority of the points follow a positive linear slope, however two of the points make the trendline inaccurate for this graph. We found the following relationships to hold true following our analysis.
Area (A) is inversely proportional to the resistance (R), the wire length (L) is directly proportional to the resistance, and the resistivity of the material (rho) is directly proportional to the resistance. The data point that does not follow the trendline in the resistance vs length graph has to do with it having a larger cross sectional area (larger diameter).
