Long description
This is a Wheatstone bridge with four resistors in a diamond configuration next to an equivalent version with the resistors arranged in a vertical rectangle. In each case, resistors R1 and R2 are connected in parallel to resistors R3 and R4. The voltage between R1 and R2 is denoted Vleft and the voltage between R3 and R4 is denoted Vright. These two points are connected across the centre of the bridge via an ammeter.