FE Other Disciplines Instrumentation and Controls

Knowledge area 4 of the FE Other Disciplines exam: 4–6 of the 110 questions. The subtopics NCEES lists, how they are tested and worked practice problems with solutions.

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110 questions on the real 5 hours 20 minutes clock, weighted to the NCEES specifications, with a score by knowledge area and a worked solution for every answer.

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What the specification lists

Sensors (e.g., temperature, pressure, motion, pH, chemical constituents)
Data acquisition (e.g., logging, sampling rate, sampling range, filtering, amplification, signal interface, signal processing, analog/digital [A/D], digital/analog [D/A], digital)
Logic diagrams

From the NCEES FE Other Disciplines CBT exam specifications, knowledge area 4.

Line drawing of a control panel with dial gauges, a thermocouple probe and a data logger

How Instrumentation and Controls is tested

Instrumentation questions cover sensors (thermocouples, RTDs, strain gauges and bridges), sampling and A/D resolution, block diagrams and closed-loop transfer functions, first- and second-order response and error propagation. The Reference Handbook section on instrumentation, measurement, and control has the relationships you need.

On exam day the relationships you need are in the Reference Handbook section on Instrumentation, Measurement, and Control. The handbook is the only reference allowed, so practice finding each formula in it rather than memorizing a separate sheet.

Start the free Instrumentation and Controls drill

FE Other Disciplines Instrumentation and Controls practice problems

Work each problem with your calculator and the handbook, then open the solution.

Problem 1 · Sensors and transducers

A platinum RTD has R₀ = 100.0 Ω at 0°C and a temperature coefficient α = 0.00385 Ω/(Ω·°C); assume R = R₀(1 + αT). The measured resistance is 119.4 Ω. Enter the temperature in °C to one decimal place.

Fill in the blank: answer in °C.

Show the answer and solution

Answer: 50.4 °C (accepted 49.9 to 50.9)

T = (R − R₀)/(αR₀) = (119.4 − 100.0)/(0.00385 × 100.0) = 19.4/0.385 = 50.4°C.

Sensors and transducers · Reference Handbook: Instrumentation, Measurement, and Control

Problem 2 · Data acquisition

A thermocouple signal is conditioned by a non-inverting op-amp amplifier with a 100 kΩ feedback resistor and a 4.7 kΩ resistor from the inverting input to ground. For a 35 mV input, the amplifier output is most nearly:

A.−0.780 V
B.−0.745 V
C.0.745 V
D.0.780 V

Show the answer and solution

Answer: D: 0.780 V

A non-inverting amplifier has gain 1 + R_f/R_g = 1 + 100/4.7 = 22.3, so V_o = 22.3(0.035) = 0.780 V with the same sign as the input. The gain R_f/R_in (21.3) applies to the inverting configuration.

Data acquisition · Reference Handbook: Instrumentation, Measurement, and Control

Problem 3 · Logic diagrams

Select all that apply.

Which of the following are logically equivalent to the NAND function (A·B)′? Select all that apply.

A.A′ + B′
B.A′ · B′
C.An OR gate whose two inputs are each inverted first
D.An AND gate followed by an inverter
E.(A + B)′

Show the answer and solution

Answer: A: A′ + B′; C: An OR gate whose two inputs are each inverted first; D: An AND gate followed by an inverter

By De Morgan's theorem, (A·B)′ = A′ + B′, which is exactly an OR gate with inverted inputs; an AND followed by an inverter is the definition of NAND. A′·B′ equals (A + B)′, which is the NOR function: it is 1 only when both inputs are 0, while NAND is 1 unless both inputs are 1.

Logic diagrams · Reference Handbook: Electrical and Computer Engineering

Problem 4 · Sensors

A glass-electrode pH probe at 25°C reads 0 mV in a pH 7.00 buffer, and its output becomes 59.16 mV more positive for each unit decrease in pH. In a process sample the probe reads +130 mV. The pH of the sample is most nearly:

A.2.20
B.2.61
C.4.80
D.9.20

Show the answer and solution

Answer: C: 4.80

ΔpH = 130/59.16 = 2.20 units. A positive reading means the sample is more acidic than the pH 7 buffer, so pH = 7.00 − 2.20 = 4.80. The 59.16 mV/pH slope is the Nernst slope for a singly charged ion (H⁺) at 25°C.

Sensors · Reference Handbook: Instrumentation, Measurement, and Control

More FE Other Disciplines practice problems from every knowledge area

Sit the full exam under the real clock

Take a full timed FE Other Disciplines practice exam

110 questions on the real 5 hours 20 minutes clock, weighted to the NCEES specifications, with a score by knowledge area and a worked solution for every answer.

Or start the free Instrumentation and Controls drill

Common questions

How many Instrumentation and Controls questions are on the FE Other Disciplines exam?

The NCEES FE Other Disciplines specification lists 4–6 questions on Instrumentation and Controls, out of 110. Every examinee gets the same number per knowledge area.

What does Instrumentation and Controls cover on the FE Other Disciplines exam?

Sensors (e.g., temperature, pressure, motion, pH, chemical constituents); Data acquisition (e.g., logging, sampling rate, sampling range, filtering, amplification, signal interface, signal processing, analog/digital [A/D], digital/analog [D/A], digital); Logic diagrams.

Where are the Instrumentation and Controls formulas on exam day?

In the NCEES FE Reference Handbook, which appears on screen during the exam: the Instrumentation, Measurement, and Control section. Practice with your free copy from MyNCEES so you know where each relationship sits.

Original independent practice questions written to the published NCEES exam specifications. Not affiliated with or endorsed by NCEES (National Council of Examiners for Engineering and Surveying).