1. Different organizational structures:
The single arm bridge is also called Wheatstone bridge, and only one of the bridge arms is the resistance to be measured;
The resistance to be measured of the double arm bridge is actually connected to two bridge arms.
2. Different functions:
Wheatstone bridge is mainly used to measure the median resistance (generally greater than 1 ohm but less than 1M ohm); The double arm extension of the double arm bridge uses the resistance connected to the voltage connector to obtain the voltage. Therefore, if the current connector is close to the inside, the measured resistance and contact resistance are too large.
Double arm resistance is mainly used to measure low value resistance (resistance less than 1 ohm). The Wheatstone bridge has eliminated the influence of the internal resistance of the ammeter on the circuit, and the influence of the conductor resistance and contact resistance on the circuit should be reduced when measuring the low resistance value resistance, so the Wheatstone bridge is improved into a Kelvin double arm bridge.
What are the similarities between double arm bridge and single arm bridge
1. Same function: all instruments are used to accurately measure resistance.
2. Both structures have bridge arms, that is, resistance, which are used to measure the change of physical quantities by the change of resistance.