3/24/2015

Results

The first lab dealt with both ideal and non-ideal power sources. Ideal power sources do not contain a resistor while non-ideal power sources incorporate a resistor. The main focus of this lab was to calculate the internal resistance of our power source which was a Analog Discovery module. We were able to calculate the internal resistance to be about 0.5Ω. However, if we were to change the resistor used in the circuit we will see that the calculated resistance will change as well. This tells us that there is more than an internal resistor being used in the Analog Discovery.

Circuit

We used a 22Ω resistor to calculate the internal resistance. 

We then learned about maximum power transfer and learned that in order to get maximum power output the resistor load must equal the resistance thevenin.

Our next lab dealt with applying the rule for maximum power transfer. For this lab we used two identical resistors that acted as the thevenin and load resistor. Since the internal resistance is so small when compared to the thevenin resistor we were able to neglect the value. We first calculated the theoretical maximum power transfer and then measured our values from the circuit and calculated an experimental maximum power.

Summary:

Today, we learned Norton's theorem and maximum power transform. Norton's theorem states that a linear two circuit terminal can be replaced with an equivalent circuit that consists of a current source in parallel with a resistor. The resistor is equivalent to the thevenin resistor. The current source can be found by dividing the voltage thevenin by the resistor thevenin. We also learned about maximum power transfer. In many situations circuits are designed to provide power to a load. For that reason it is important to transfer maximum power to  the load and in order to do that the load resistance should equal the thevenin resistance. We also learned that power sources contain an internal resistance and a method in which to calculate the resistance.