Asee peer logo

A Hydrodynamic Wheatstone Bridge For Use As A Teaching Tool In Instrumentation Laboratory Courses

Download Paper |


2006 Annual Conference & Exposition


Chicago, Illinois

Publication Date

June 18, 2006

Start Date

June 18, 2006

End Date

June 21, 2006



Conference Session

Innovative and Computer-Assisted Lab Studies

Tagged Division

Division Experimentation & Lab-Oriented Studies

Page Count


Page Numbers

11.56.1 - 11.56.11



Permanent URL

Download Count


Request a correction

Paper Authors

author page

David Bloomquist University of Florida

author page

Michael McVay University of Florida

author page

Scott Wasman University of Florida

author page

Clinton Slatton University of Florida

Download Paper |

NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract



Undergraduate engineering students often find systems composed of electrical circuits difficult to grasp because variables such as current, voltage, resistance, capacitance, and inductance are not easily visualized as their analogs in mechanical systems. Thus, a Hydrodynamic Wheatstone bridge, using the analogy of flow in pipes, was developed to serve as a teaching tool in the classroom. A series of tests were performed to simulate ¼, ½, full, and shunted bridge circuits, where the increase or decrease in resistance in the strain gage is analogous to partially closing or opening a valve in a pipe network. The difference in head potential (i.e., ∆V) was measured with manometers located between the valves. The results agree with the ¼, ½, full, and shunted Wheatstone bridge circuits. Future enhancements include the addition of flow meters to relate water flow to current flow, scaled full turn valves to more accurately represent changing resistances, and a flexible tube section, in place of a valve, to replicate a strain gage in tension.


In 1994, Civil Engineering professors at the University of Florida developed an undergraduate course, "INSTRUMENTATION FOR ENGINEERS", in which students are exposed to the fundamentals of circuitry through basic analysis of DC and AC circuits. Exercise problems are routinely performed in the classroom and given to the students for reinforcement through independent practice. Accompanying the course is a weekly two hour lab which provides the students hands on practice with civil engineering instrumentation: e.g., load cells, displacement transducers (LVDT), accelerometers, and pressure transducers. Since the Wheatstone bridge circuit is frequently used in these instruments, analysis of it is paramount to the students’ success in the course. Unfortunately, this topic is one that causes the most angst (perhaps second only to Thevenins!), and thus we felt it would be helpful to develop a device that would allow the students to observe what happens to water pressures when flowing in a “bridge circuit” pipe network.

Hence, using the analogy of flow in pipes, a bridge circuit was developed as a teaching tool. The similarity between hydrodynamics (flow, pressure, and valve position) to electricity (current, voltage, and resistance) provides a useful analogy. For example, a strain gage in a bridge circuit can be modeled with a needle valve in a pipe network so that an increase or decrease in resistance (via tension or compression) in the strain gage is analogous to closing or opening a valve in a pipe system. This will, in turn, create a ∆V (assuming a ¼ bridge) that can be represented by a difference in water heights in manometers located at the mid-points of the “bridge”.

Similarly, ½, full, and shunted bridge circuits can be modeled depending on the valve settings. For example, the students can 'balance' the bridge by adjusting the valves until the water heights in the manometers are equal. Then, by opening (less resistance = compression of a gage) one or

Bloomquist, D., & McVay, M., & Wasman, S., & Slatton, C. (2006, June), A Hydrodynamic Wheatstone Bridge For Use As A Teaching Tool In Instrumentation Laboratory Courses Paper presented at 2006 Annual Conference & Exposition, Chicago, Illinois. 10.18260/1-2--1331

ASEE holds the copyright on this document. It may be read by the public free of charge. Authors may archive their work on personal websites or in institutional repositories with the following citation: © 2006 American Society for Engineering Education. Other scholars may excerpt or quote from these materials with the same citation. When excerpting or quoting from Conference Proceedings, authors should, in addition to noting the ASEE copyright, list all the original authors and their institutions and name the host city of the conference. - Last updated April 1, 2015