02 Sensors Problem Set
SENSORS | PRACTICE PROBLEMS
Complete the following to reinforce your understanding of the concept covered in this module.
PROBLEM 1: The platinum resistance thermometer is used to measure the temperature an environment of an undefined period of time. Given the resistance values below, the sensitivity of the platinum resistance thermometer is closest too: ๐ผ๐๐๐ข๐ก: ๐๐๐๐๐๐๐๐ก๐ข๐๐ (ยฐ๐ถ)
๐๐ข๐ก๐๐ข๐ก: ๐ ๐๐ ๐๐ก๐๐ฃ๐๐ก๐ฆ (๐บ)
307
200
314
230
321
260
328
290
A. 0.138 B. 0.233 C. 0.488 D. 0.721
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SOLUTION 1:
The formula for SENSITIVITY is not provided in the NCEES Supplied Reference Handbook, Version 9.4 for Computer Based Testing. We must memorize this formula and understand its application independent of the NCEES Supplied Reference Handbook. The SENSITIVITY is defined as the ratio of the change in output to the corresponding change in input under static or steady state conditions
๐๐๐๐ ๐๐ก๐๐ฃ๐๐ก๐ฆ =
๐ถโ๐๐๐๐ ๐๐ ๐ผ๐๐๐ข๐ก ๐ถโ๐๐๐๐ ๐๐ ๐๐ข๐ก๐๐ข๐ก
Looking at the values provide for the inputs, which is temperature in units 0f ยฐ๐ถ, we see there is a common difference of 30ยฐ๐ถ for each interval. Switching over the outputs, which is resistance in units of ๐บ, we see there is a common difference of 7 ๐บ per interval. Plugging these values into the formula for sensitivity, we find:
๐๐๐๐ ๐๐ก๐๐ฃ๐๐ก๐ฆ =
7 ๐บ = 0.233 30 ยฐ๐ถ
Therefore, the correct answer choice is B. ๐. ๐๐๐
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PROBLEM 2: An operator at a power plant used a pH sensor to measure the pH of a solution near the steam drum of the facility. If the sensor gives a negative output, which of the following statements is true? A. ๐โ๐ ๐ ๐๐๐ข๐ก๐๐๐ ๐๐ ๐๐๐๐๐๐ B. ๐โ๐ ๐ ๐๐๐ข๐ก๐๐๐ ๐๐ ๐๐๐ ๐๐ C. ๐โ๐ ๐ ๐๐๐ข๐ก๐๐๐ ๐๐ ๐๐๐ข๐ก๐๐๐ D. ๐๐๐๐ ๐๐ ๐กโ๐ ๐๐๐๐ฃ๐
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SOLUTION 2:
The formula for the RELATIONSHIP GOVERNING A PH SENSOR can be referenced under the topic of INSTRUMENTATION, MEASUREMENT, AND CONTROLS on page 126 of the NCEES Supplied Reference Handbook, Version 9.4 for Computer Based Testing. The voltage output reading for a pH sensor is directly proportional to the pH of the solution. Therefore, at a pH of 7 (neutral) the output would be 0, and then produce a negative reading for an acidic reading (pH < 7) and a positive reading for a basic reading (pH > 7).
Therefore, the correct answer choice is A. ๐๐ก๐ ๐ฌ๐จ๐ฅ๐ฎ๐ญ๐ข๐จ๐ง ๐ข๐ฌ ๐๐๐ข๐๐ข๐
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PROBLEM 3:
Which of the following sensor types is NOT suitable for a combustible hydrocarbon analyte? A. ๐๐๐๐๐๐๐๐๐ข๐๐ก๐๐๐ ๐๐ฅ๐๐๐ ๐ ๐๐๐ ๐๐ B. ๐๐๐๐๐ ๐๐๐๐๐ก๐๐๐๐ ๐ ๐๐๐ ๐๐ C. ๐๐๐๐ง๐๐๐๐๐๐ก๐๐๐ ๐ ๐๐๐ ๐๐ D. ๐๐ฆ๐๐๐๐๐๐๐ก๐๐๐ ๐ ๐๐๐ ๐๐
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SOLUTION 3: The table for EXAMPLES OF COMMON CHEMICAL SENSORS can be referenced under the topic of INSTRUMENTATION, MEASUREMENT, AND CONTROLS on page 126 of the NCEES Supplied Reference Handbook, Version 9.4 for Computer Based Testing.
Looking at the table for examples of common chemical sensor, we notice that all of the listed sensor types are listed accepted for a combustible hydrocarbon except a pyroelectric sensor.
Therefore, the correct answer choice is D. ๐ท๐๐๐๐๐๐๐๐๐๐๐ ๐๐๐๐๐๐
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PROBLEM 4: An engineer at a local industrial facility is looking to measure the pressure inside a pressurized gas duct relative to another pressurized gas duct nearby. What type of pressure measurement type should be used? A. ๐ด๐๐ ๐๐๐ข๐ก๐ B. ๐บ๐๐๐ C. ๐ท๐๐๐๐๐๐๐๐ก๐๐๐ D. ๐๐๐๐๐๐
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SOLUTION 4:
The table for PRESSURE RELATIVE MEASUREMENT TYPES can be referenced under the topic of INSTRUMENTATION, MEASUREMENT, AND CONTROLS on page 126 of the NCEES Supplied Reference Handbook, Version 9.4 for Computer Based Testing. Pressure Relative Measurement Types
Comparison
Absolute
Relative to 0 Pa, the pressure in a vacuum
Gage
Relative to local atmospheric pressure Relative to either absolute vacuum (0 Pa) or local
Vacuum
atmospheric pressure
Differential
Relative to another pressurized container
Sealed
Relative to sea level pressure
As the engineering is look to measure the pressure inside a pressurized container relative to another pressurized container, the measurement would be considered DIFFERENTIAL.
Therefore, the correct answer choice is C. ๐ซ๐๐๐๐๐๐๐๐๐๐๐
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Complete the following to reinforce your understanding of the concept covered in this module.
PROBLEM 1: The platinum resistance thermometer is used to measure the temperature an environment of an undefined period of time. Given the resistance values below, the sensitivity of the platinum resistance thermometer is closest too: ๐ผ๐๐๐ข๐ก: ๐๐๐๐๐๐๐๐ก๐ข๐๐ (ยฐ๐ถ)
๐๐ข๐ก๐๐ข๐ก: ๐ ๐๐ ๐๐ก๐๐ฃ๐๐ก๐ฆ (๐บ)
307
200
314
230
321
260
328
290
A. 0.138 B. 0.233 C. 0.488 D. 0.721
Made with
by Prepineer | Prepineer.com
SOLUTION 1:
The formula for SENSITIVITY is not provided in the NCEES Supplied Reference Handbook, Version 9.4 for Computer Based Testing. We must memorize this formula and understand its application independent of the NCEES Supplied Reference Handbook. The SENSITIVITY is defined as the ratio of the change in output to the corresponding change in input under static or steady state conditions
๐๐๐๐ ๐๐ก๐๐ฃ๐๐ก๐ฆ =
๐ถโ๐๐๐๐ ๐๐ ๐ผ๐๐๐ข๐ก ๐ถโ๐๐๐๐ ๐๐ ๐๐ข๐ก๐๐ข๐ก
Looking at the values provide for the inputs, which is temperature in units 0f ยฐ๐ถ, we see there is a common difference of 30ยฐ๐ถ for each interval. Switching over the outputs, which is resistance in units of ๐บ, we see there is a common difference of 7 ๐บ per interval. Plugging these values into the formula for sensitivity, we find:
๐๐๐๐ ๐๐ก๐๐ฃ๐๐ก๐ฆ =
7 ๐บ = 0.233 30 ยฐ๐ถ
Therefore, the correct answer choice is B. ๐. ๐๐๐
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PROBLEM 2: An operator at a power plant used a pH sensor to measure the pH of a solution near the steam drum of the facility. If the sensor gives a negative output, which of the following statements is true? A. ๐โ๐ ๐ ๐๐๐ข๐ก๐๐๐ ๐๐ ๐๐๐๐๐๐ B. ๐โ๐ ๐ ๐๐๐ข๐ก๐๐๐ ๐๐ ๐๐๐ ๐๐ C. ๐โ๐ ๐ ๐๐๐ข๐ก๐๐๐ ๐๐ ๐๐๐ข๐ก๐๐๐ D. ๐๐๐๐ ๐๐ ๐กโ๐ ๐๐๐๐ฃ๐
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SOLUTION 2:
The formula for the RELATIONSHIP GOVERNING A PH SENSOR can be referenced under the topic of INSTRUMENTATION, MEASUREMENT, AND CONTROLS on page 126 of the NCEES Supplied Reference Handbook, Version 9.4 for Computer Based Testing. The voltage output reading for a pH sensor is directly proportional to the pH of the solution. Therefore, at a pH of 7 (neutral) the output would be 0, and then produce a negative reading for an acidic reading (pH < 7) and a positive reading for a basic reading (pH > 7).
Therefore, the correct answer choice is A. ๐๐ก๐ ๐ฌ๐จ๐ฅ๐ฎ๐ญ๐ข๐จ๐ง ๐ข๐ฌ ๐๐๐ข๐๐ข๐
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PROBLEM 3:
Which of the following sensor types is NOT suitable for a combustible hydrocarbon analyte? A. ๐๐๐๐๐๐๐๐๐ข๐๐ก๐๐๐ ๐๐ฅ๐๐๐ ๐ ๐๐๐ ๐๐ B. ๐๐๐๐๐ ๐๐๐๐๐ก๐๐๐๐ ๐ ๐๐๐ ๐๐ C. ๐๐๐๐ง๐๐๐๐๐๐ก๐๐๐ ๐ ๐๐๐ ๐๐ D. ๐๐ฆ๐๐๐๐๐๐๐ก๐๐๐ ๐ ๐๐๐ ๐๐
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SOLUTION 3: The table for EXAMPLES OF COMMON CHEMICAL SENSORS can be referenced under the topic of INSTRUMENTATION, MEASUREMENT, AND CONTROLS on page 126 of the NCEES Supplied Reference Handbook, Version 9.4 for Computer Based Testing.
Looking at the table for examples of common chemical sensor, we notice that all of the listed sensor types are listed accepted for a combustible hydrocarbon except a pyroelectric sensor.
Therefore, the correct answer choice is D. ๐ท๐๐๐๐๐๐๐๐๐๐๐ ๐๐๐๐๐๐
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PROBLEM 4: An engineer at a local industrial facility is looking to measure the pressure inside a pressurized gas duct relative to another pressurized gas duct nearby. What type of pressure measurement type should be used? A. ๐ด๐๐ ๐๐๐ข๐ก๐ B. ๐บ๐๐๐ C. ๐ท๐๐๐๐๐๐๐๐ก๐๐๐ D. ๐๐๐๐๐๐
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SOLUTION 4:
The table for PRESSURE RELATIVE MEASUREMENT TYPES can be referenced under the topic of INSTRUMENTATION, MEASUREMENT, AND CONTROLS on page 126 of the NCEES Supplied Reference Handbook, Version 9.4 for Computer Based Testing. Pressure Relative Measurement Types
Comparison
Absolute
Relative to 0 Pa, the pressure in a vacuum
Gage
Relative to local atmospheric pressure Relative to either absolute vacuum (0 Pa) or local
Vacuum
atmospheric pressure
Differential
Relative to another pressurized container
Sealed
Relative to sea level pressure
As the engineering is look to measure the pressure inside a pressurized container relative to another pressurized container, the measurement would be considered DIFFERENTIAL.
Therefore, the correct answer choice is C. ๐ซ๐๐๐๐๐๐๐๐๐๐๐
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