Pre-lab Tasks:

Consider the circuit shown in figure 15. This circuit consists of a 5 volt independent voltage source driving a resistive circuit with a single diode. One of the resistors is a 100 ohm resistor. The other resistor is a variable resistor whose value can be changed between 0 and 10 kilo ohms. Since the second resistor's value is variable, the second resistor's value is denoted by the variable $R$.

Figure 15: Circuit for Lab 1

Before coming to the lab you should do the following:

1. Draw a labelled schematic diagram of the circuit with an explanation of how the circuit works.
2. Draw a picture showing how you plan to breadboard the circuit.
3. Derive an expression for the current going through the diode as a function of the variable resistance, $R$.
4. Plot the current through the LED as a function of the variable resistance $R$.

Ask the TA to check your completed pre-lab analysis. If your answers are correct, then you can proceed to the In-lab task.