Feb 26, Dependent Sources and MOSFETS

In the beginning of class, we are asked to make a prediction about what will happen if the switch is closed in the circuit shown below. 


As we can see from the picture, the brightness of the two bulb stay unchanged.

Circuit and measured values
The circuit for this lab. 

1.measured resistance of resistor R=100.3

Above is real circuit of the lab.

Above is the measurement of the lab. 

3.

2.From the data table the threshold voltage is approximately 1.5V. Because current appears when voltage goes above 1.5V. 

4.The transistor is behaving like a voltage dependent current source because the transistor control the current go through the circuit based on the voltage on the gate.

5.estimate g is 4.959

I pick the linear part of the plot and find the slope of best fit line of the graph.The slope obtained by Excel is 4.949 which is the g for circuit.

Summary:

In this lab we learn how a dependent source work. MOSFETS works like a dependent source and we will use its linear region.IN this lab the uncertainty comes from the inaccurate reading of multimeter. The source of error may be the influence caused by the multimeter.