PTC Lamp filament, Lab part B

In the major lab #1, we set up  a circuit to see the effect of current and voltage drop in two wire wound resistors.

Part B of that lab, I modified the voltages as shown below and gained a nice non-linear graph of lamp filament voltage.  There are 8 steppings in the circuit voltage, starting at 2 Volts and going to 9 Volts.

PTC Lamp filament resistance