12-Mar-2015: Mesh analysis

Today, we further developed our understanding of mesh analysis. We applied this newly acquired knowledge by solving for the current across a resistor and the voltage across another. Then, we set up a circuit to compare the theoretical and experimental values.

(Figure 1)

We began the day by taking a quiz during which we solved for i1 and i using mesh analysis (Figure 1). We found i1 by solving for the system of equations that we got from applying KVL across each mesh, or independent loop. From this system of equation, we also found i2 and i3. We solved for i from these values by subtracting i2 from i3. We did this because we saw that i3 went in the same direction as i, while i2 went in the opposite direction.

(Figure 2)

After the quiz, we learned about supermeshes. A supermesh is composed of two meshes that have a common current source. Then, we learned about diodes, which are semiconductor devices that are made up of (to be continued...) For more information on supermeshes, diodes, and transistors, refer to the Day 6 lecture posted on profmason.com. After the lecture, we did a lab in which we implemented the concepts that we studied in class to a real-life situation. Before setting up the circuit, we first calculated I1 and V1 by utilizing mesh analysis, shown on the left side of Figure 2. We then used a multimeter to measure the actual resistance values of the 1.8 Ω, 22 Ω, 6.8 Ω, and 4.7 Ω resistors, respectively, shown on the right side of Figure 2.

(Figure 3)

Next, we set up the circuit on a breadboard. The completed circuit is shown above (Figure 3). Note that we labeled the two voltage sources and the ground cable above the circuit in terms of the color of the wires and the color of the clips, respectively.

(Figure 4)

(Figure 5)

After completing the circuit, we turned on the voltage sources and measured the current running through the 1.8 Ω resistor and the voltage across the 22 Ω resistor. Figure 4 shows us measuring the current across 1.8 Ω resistor, while Figure 5 lists the experimental and theoretical voltage values across the 22 Ω resistor, respectively.