The same points: 1. They are both instruments used to accurately measure resistance; 2. Both have bridge arms in structure, that is, resistance, and they all use changes in resistance to measure changes in physical quantities. Difference: Wheatstone bridge is mainly used to measure the median resistance, that is, resistance generally greater than 1 ohm and less than 1M ohm; double-arm resistance is mainly used to measure low-value resistance, that is, resistance less than 1 ohm.
The similarities between the double-arm bridge and the Wheatstone bridge:
1. The functions are the same: They are all instruments used to accurately measure resistance.
2. They all have bridge arms in structure, that is, resistance, and they all use changes in resistance to measure changes in physical quantities.
The differences between the double-arm bridge and the Wheatstone bridge:
1. Different structures
1. Wheatstone bridge Also called a single-arm bridge, only one of the bridge arms is the resistance to be measured;
2. The resistance to be measured of the double-arm bridge is actually connected to the two bridge arms.
2. Different practical applications
1. The Wheatstone bridge is mainly used to measure the median resistance (generally a resistance greater than 1 ohm and less than 1M ohm);
When the arms of the double-arm bridge are extended, the resistance connected to the voltage connector is used to divide the voltage. Therefore, if the current connector is closer to the inside, the measured resistance and contact resistance will be measured, so it is too large.
2. The double-arm resistor is mainly used to measure low-value resistance (resistance less than 1 ohm).
Because the Wheatstone bridge has eliminated the impact of the internal resistance of the meter on the circuit, and when measuring low-resistance resistance, it is necessary to reduce the impact of the wire resistance and contact resistance on the circuit, so the Wheatstone bridge has been improved to Kelvin double arm bridge.
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