This circuit demonstrates how GATE and DRAIN voltages cross the MOSFET transistor drive the change of DRAIN-to-SOURCE current.
Transistor behaves as a varying resistor which resistance depends on the GATE and DRAIN voltages. The effects of varying resistance across the DRAIN and SOURCE is measured by the Ohmmeters in the middle of the circuit.
Finally you can observe how the WIDTH of the MOSFET channel affects the resistance and current. Doubling the width of the channel (from 1 micron to 2 microns) reduces the resistance by half and doubles the current.
