Search results
Results from the WOW.Com Content Network
A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. The primary benefit of the circuit is its ability to provide extremely accurate measurements (in contrast with something like a simple voltage divider ). [ 1 ]
The best-known bridge circuit, the Wheatstone bridge, was invented by Samuel Hunter Christie and popularized by Charles Wheatstone, and is used for measuring resistance. It is constructed from four resistors, two of known values R 1 and R 3 (see diagram), one whose resistance is to be determined R x , and one which is variable and calibrated R 2 .
The post office box was a Wheatstone bridge–style testing device with pegs and spring arms to close electrical circuits and measure properties of the circuit under test. [ 1 ] [ 2 ] Resistance measurement
A standard Wheatstone bridge for comparison. Points A, B, C and D in both circuit diagrams correspond. X and Y correspond to R 1 and R 2, P and Q correspond to R 3 and R X. Note that with the Carey Foster bridge, we are measuring R 1 rather than R X. Let ℓ 1 be the null point D on the bridge wire EF in percent.
Temperature effects on the lead wires can be cancelled by using a "3-wire bridge" or a "4-wire ohm circuit" [7] (also called a "4-wire Kelvin connection"). In any case it is a good engineering practice to keep the Wheatstone bridge voltage drive low enough to avoid the self heating of the strain gauge.
A Maxwell-Wien bridge. A Maxwell bridge is a modification to a Wheatstone bridge used to measure an unknown inductance (usually of low Q value) in terms of calibrated resistance and inductance or resistance and capacitance. [1] When the calibrated components are a parallel resistor and capacitor, the bridge is known as a Maxwell bridge.
The Wien bridge does not require equal values of R or C. At some frequency, the reactance of the series R 2 –C 2 arm will be an exact multiple of the shunt R x –C x arm. If the two R 3 and R 4 arms are adjusted to the same ratio, then the bridge is balanced. The bridge is balanced when: [4]
Since the change in resistance measured by a single strain gauge is extremely small, it is difficult to accurately measure changes. Increasing the number of strain gauges applied collectively magnifies these small changes into something more measurable. A set of 4 strain gauges set in a specific circuit is an application of a Wheatstone bridge.