Ch 5: Wheatstone Bridge Flashcards
Q: What is a Wheatstone bridge?
A: A circuit used to measure unknown resistance by balancing two legs of a bridge circuit.
Q: Define strain gauge.
A: A sensor that measures strain on an object by detecting changes in resistance.
Q: What is a cantilever biosensor?
A: A device that detects changes in mass or stress by measuring cantilever deflection.
Q: What is bridge balance?
A: A condition where the voltage difference across the Wheatstone bridge is zero.
Q: What is the function of a Wheatstone bridge in strain measurement?
A: To detect minute resistance changes caused by strain.
Q: What is the sensitivity of a Wheatstone bridge?
A: Its ability to detect small changes in resistance.
Q: Why is a Wheatstone bridge used with thermistors?
A: To measure temperature changes more accurately.
Q: What is the output of a Wheatstone bridge?
A: A differential voltage signal proportional to resistance changes.
Q: How do you balance a Wheatstone bridge?
A: By adjusting the resistors so that the voltage difference is zero.
Q: What is a quarter-bridge circuit?
A: A Wheatstone bridge configuration where one resistor is replaced by a strain gauge.
Q: What is a full-bridge circuit?
A: A configuration where all four resistors are active strain gauges.
Q: What is a half-bridge circuit?
A: A Wheatstone bridge with two active strain gauges and two fixed resistors.
Q: What are the advantages of a Wheatstone bridge?
A: High accuracy and sensitivity in measuring resistance changes.
Q: What is bridge excitation voltage?
A: The voltage applied across the Wheatstone bridge.
Q: Why is temperature compensation important in strain gauges?
A: To eliminate errors caused by temperature-induced resistance changes.
Q: How is a Wheatstone bridge used in pressure sensors?
A: To detect changes in
Q: How do you calculate R4 in a balanced Wheatstone bridge?
A: Use the equation R1 × R3 = R2 × R4.
Q: What does a decreased resistance in a strain gauge indicate?
A: Compression of the strain gauge.
Q: What is the balanced resistance of R4 when R1 = 118 Ω, R2 = 120 Ω, and R3 = 122 Ω?
A: R4 = 120 Ω.
Q: How does touching a strain gauge affect its resistance?
A: It changes based on the strain, increasing for stretching and decreasing for compression.
