Week 4 Day 1

Mesh analysis practice:

Pre-lab : Find the theoretical value of current and voltage drop across 10 K ohm resistor and the voltage drop across 6.8 K ohm resistor.

We measured  the actual resistance in 6.8 K, 22 K 4.7 K and 21.6 K resistor using digital multi meter:

Below are the measured value of each resistor with uncertainty of 0.01 K ohm

Picture of our circuit :

Measured value of potential drop across 6.8 K resistor :

Measured value of current through 10 K resistor

Measured value of potential drop through 10 K resistor:

Below are the compared theoretical and experimental values; V1 represent the voltage drop on 6.8 K resistor, V2 represent the voltage drop on 10 K resistor and I1 represent the current flow through 10 K resistor:

Transistor Lecture

Calculating current through a diode and minimum resistance needed, 0.7 V comes from the voltage drop by silicon transistor :

Converting transistor into a circuit and calculating the power dissipated through resistor :

Calculating the minimum resistance needed for transistor with 0.5 Watt capacity:

Summary 

Mesh analysis is best used on circuits with multiple series component and voltage sources, while nodal analysis is best used on circuits with multiple parallel component and current sources. Instead of solving mesh analysis algebraically by going through the entire loop, we can set up mesh equation by inspecting total resistor that a current passes through the loop. Transistor works by combining positively doped and negatively doped semi conductor. There are two type of resistor: NPN, which have a positively charged base and PNP, with negatively charge base.  Transistor works to amplify current.