2/26/2015

We began the day with a circuit puzzle. We were asked to explain what would happen to the light bulbs when the switch was closed.

Switch open

Switch closed

Lab set-up

The first lab consisted of supplying a certain amount of voltage through a 100 ohm resistor. We supplied different amounts of voltage using a program called WaveForms.

Measuring the resistance of the resistor

We first measured the resistance of the resistor which was found to be 97.4 ohms.

Results

We then supplied different voltages across the resistor using WaveForms and then measured the current for each voltage.

Circuit diagram for lab

Graph of Current Vs. Voltage

It was found that the relationship between current and voltage was linear. (V=IR)

Lab set-up

The second lab required the use of a MOSFET and a 100 ohm resistor. The purpose of this lab was to determine the threshold voltage. We did this by increasing the voltage across the MOSFET incrementally and measuring the current. When the current begins to be roughly the same as the voltage is increases, we have determined the threshold. 

Results

We determined that the MOSFET voltage threshold was roughly 2.5 volts.

Summary:
The day consisted of learning or relearning ohm's law and Kirchhoff's loop law. Kirchhoff's loop law states that in a closed circuit the sum of voltages is equal to zero. Ohm's law states that the current through a circuit between two points is directly proportional to the potential difference across the two points.