2N3904 Transistor

To get a better understanding of how transistor work, we were given a lab manual to put a NPN 2N3904 transistor in a circuit and measure current through its base and emitter. We made changes to values of the current by changing the resistance value in the resistor box.

the schematic for the circuit is as follow:

 

Without even graphing the linear relationship between the currents presents itself. As values of base currents increase the values for the emitter current change with almost the same amount.

Since I_E=(1+β)I_B then the equation for emitter current as a function of times becomes:

 

I_E=I_B+βI_B , when compared to y=mx+b we can deduce that the β is the slope of the graph and the I_B is the initial value. As a result β=0.968 and I_B = 3.73. this value of base emitter is where the linear portion of their relationship starts. Also if we use resistor values below 1.9K or above 10K ohm we will be out of the linear portion of the currents relationships.