Sunday, March 3, 2013

Introduction to DC Circuits

In this lab we had to determine the maximum length that the cable (AWG #30) could be so that the 12 V battery could provide a voltage across the load that is greater than 11 V.
In order to determine the length we first combine the resistance of the two cables calling the resistance Rtot and treat it as a single resistor. We used a battery to provide a steady 12 V and a resistor box to act as the cable. A fixed resistor was used to represent the load. The theoretical value for the Rload is 1000 ohms. However our resistor measured around 980 ohms. We would slowly increment the resistance until we measured close to 11 V across the load. At 11 V we measured a current of 11.44 mA and a resistance of 84 ohms across the cable.


Based on the data we collected we determine the length of the cable to be 121.7 m.

AWG #30 resistance = 0.3451 ohms/ m
Rtot = 84 ohms
Rtot / AWG #30 = 243.4 m 
243.4 m / 2 = length of cable = 121.7 m