Day two

In the beginning of the class, professor Mason shows us a current circle there are top and bot two light. In the top light we connect a voltage to it, and guess what will happen.

We guess that both the top light and the bot light will stay the same. 

In this lab, when the third voltage is open, we know the top and bot light both have the voltage 3V, When we close the on/off, the top light's voltage is still 3V(same potential energy), so there is not more power goes though it. for the bot light, it is still stay at 3V, so it is stay same too.

In this lab, we use WaveForm to apply power, and connect it with a 100 ohm resistor. 

The experiment set up 

We measure the true resistor is 100.9ohm, Then we use experiment to find the experiment ohm

Do ing the experiment, and recording the data.

After recording the data, we use data to make a graph

In the graph of Voltage vs. Current. we find an equation y=103.6x+0.0035. In the equation, the slope 103.6 is the resistor, so that the % difference is (100.9-103.6)/100.9*100% = -2.67%

3. In this lab, we are going to use a MOSFET and a 100 ohm resistor. We have a resistor which has a true value of 100.9 ohm. We are going to determine the threshold voltage of the MOSFET. If the voltage is below the gate voltage, there won’t be any significant current. With MOSFET, we can increase the power supply’s current by increasing the gate voltage. A MOSFET and a power supply, can act as a voltage controlled current source in which the drain current is controlled by the gate voltage.

 The set up of the experiment. We at first use the regular power supply. After figuring how to use the waveform, we do a new experiment with waveform.

The circuit of the experiment

In the experiment, we connect a 5 V voltage source, and we goes to supply other different voltages to the MOSFET. In the experiment, we see the rank of voltage is from 2.0 V to 2.5 V, so we guess the gate voltage is 2.5 V. 

Gate Voltage vs. Drain Current Graph.

In the graph, we can see when the voltage is below than 2.0V, it increases slowly. And after 2.5V, the voltage goes to increase slowly again. so we guess the threshold should be 2.0. The input voltage control current.