The type of network involving potentiometer

[DrunkApple]

Homework Statement

Adjust the potentiometer to get V$_{0}$ = 0 V(V$_{a}$ - V$_{b}$). What is this network called?

Homework Equations

The Attempt at a Solution

I'll be honest. This professor didn't even prepare for the lab and decided to do lab about the potentiometer we didn't even learn about. So if V = 0 in the circuit, does anyone know what network that is called?

 

[wukunlin]

what does the circuit look like?