Introduction to DC Circuits

The Introduction to DC Circuits Lab started off with a simple concept pictured below.

Real world application must take into account the natural resistivity of the material that conducting cables are made of.

In this set up, a current flows from the battery through the cable to the "load" then back to the battery again. In a perfect world, all resistance in this system would come from the load and up until now we've taken for granted that all theoretical cables are perfect conductors. The real world is not as forgiving however, and cables themselves (regardless of material) have inherent resistances.

Starting with the red cable (farthest right): Current flows from DC power supply to a resistor box then into a current meter and then into a 1000 Ohm resistor (which simulates the load). The voltage across the resistor is also measured by a voltmeter.

This comes into play when designing real life applications that require current to be transported over long distances; the conductivity and resistance of the material must be accounted for because it will make a difference in the overall system. To demonstrate this, we set up the following lab (pictured on the right).

What we found (aside from the fact that none of the equipment outputted the exact amounts stated on its labels; I.E 12V power supply actually put out 12.18V) was that there is a maximum length that exists for which the current could not effectively carried past that.