A circuit for measuring an unknown resistance using a quadrilateral with three known resistors is called

A circuit for measuring an unknown resistance using a quadrilateral with three known resistors is called

• A. Ohmmeter Circuit
• B. Wheatstone Bridge Circuit
• C. Kelvin Bridge
• D. Potentiometer

Answer: (B)

Balancing a four-resistor bridge to determine an unknown resistance is the idea behind a Wheatstone bridge. The circuit is arranged like a diamond with four arms: two known resistors in one leg and two in the other leg, with the unknown resistor in one of those arms. A detector sits between the midpoints of the two legs. When the bridge is balanced, no current flows through the detector, and the ratios of the resistors satisfy R1/R2 = R3/Rx. From this relationship you can solve for the unknown resistance: Rx = R3 × (R2/R1). This null-condition setup lets you measure resistance very accurately because it cancels out errors from the detector and lead resistances. The other options refer to different measurement devices or methods: an ohmmeter measures resistance by applying current and reading the resulting voltage; a Kelvin bridge is a four-terminal method optimized for very low resistances to minimize contact resistance errors; and a potentiometer measures an unknown EMF by comparing potentials rather than resistance.

Balancing a four-resistor bridge to determine an unknown resistance is the idea behind a Wheatstone bridge. The circuit is arranged like a diamond with four arms: two known resistors in one leg and two in the other leg, with the unknown resistor in one of those arms. A detector sits between the midpoints of the two legs. When the bridge is balanced, no current flows through the detector, and the ratios of the resistors satisfy R1/R2 = R3/Rx. From this relationship you can solve for the unknown resistance: Rx = R3 × (R2/R1). This null-condition setup lets you measure resistance very accurately because it cancels out errors from the detector and lead resistances.

The other options refer to different measurement devices or methods: an ohmmeter measures resistance by applying current and reading the resulting voltage; a Kelvin bridge is a four-terminal method optimized for very low resistances to minimize contact resistance errors; and a potentiometer measures an unknown EMF by comparing potentials rather than resistance.