No voltage difference between driven MOSFET gate and floating drain/source

Question

I'm measuring the voltage of a discrete MOSFET using a multimeter. The gate is connected to the output of a logic circuitry, while drain and source are floating. The voltage difference between drain/source and ground is random as expected. But when I connect the multimeter between the gate and drain/source, the voltage difference is less than a 1 mV.

Why is that?

Answer 1

The same thing happens with a capacitor, and for the same reason.

The connection between the gate and drain/source is like a capacitor. If you leave the drain and source floating, they will tend to follow the gate because they are capacitively coupled. If they didn't, you would be putting energy into that junction.