Ch 5: Wheatstone Bridge Flashcards

1
Q

Q: What is a Wheatstone bridge?

A

A: A circuit used to measure unknown resistance by balancing two legs of a bridge circuit.

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2
Q

Q: Define strain gauge.

A

A: A sensor that measures strain on an object by detecting changes in resistance.

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3
Q

Q: What is a cantilever biosensor?

A

A: A device that detects changes in mass or stress by measuring cantilever deflection.

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4
Q

Q: What is bridge balance?

A

A: A condition where the voltage difference across the Wheatstone bridge is zero.

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5
Q

Q: What is the function of a Wheatstone bridge in strain measurement?

A

A: To detect minute resistance changes caused by strain.

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6
Q

Q: What is the sensitivity of a Wheatstone bridge?

A

A: Its ability to detect small changes in resistance.

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7
Q

Q: Why is a Wheatstone bridge used with thermistors?

A

A: To measure temperature changes more accurately.

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8
Q

Q: What is the output of a Wheatstone bridge?

A

A: A differential voltage signal proportional to resistance changes.

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9
Q

Q: How do you balance a Wheatstone bridge?

A

A: By adjusting the resistors so that the voltage difference is zero.

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10
Q

Q: What is a quarter-bridge circuit?

A

A: A Wheatstone bridge configuration where one resistor is replaced by a strain gauge.

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11
Q

Q: What is a full-bridge circuit?

A

A: A configuration where all four resistors are active strain gauges.

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12
Q

Q: What is a half-bridge circuit?

A

A: A Wheatstone bridge with two active strain gauges and two fixed resistors.

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13
Q

Q: What are the advantages of a Wheatstone bridge?

A

A: High accuracy and sensitivity in measuring resistance changes.

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14
Q

Q: What is bridge excitation voltage?

A

A: The voltage applied across the Wheatstone bridge.

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15
Q

Q: Why is temperature compensation important in strain gauges?

A

A: To eliminate errors caused by temperature-induced resistance changes.

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16
Q

Q: How is a Wheatstone bridge used in pressure sensors?

A

A: To detect changes in

17
Q

Q: How do you calculate R4 in a balanced Wheatstone bridge?

A

A: Use the equation R1 × R3 = R2 × R4.

18
Q

Q: What does a decreased resistance in a strain gauge indicate?

A

A: Compression of the strain gauge.

19
Q

Q: What is the balanced resistance of R4 when R1 = 118 Ω, R2 = 120 Ω, and R3 = 122 Ω?

A

A: R4 = 120 Ω.

20
Q

Q: How does touching a strain gauge affect its resistance?

A

A: It changes based on the strain, increasing for stretching and decreasing for compression.