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Sensors and Industrial Instrumentation

26 Questions
GATE→2026→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q1
MCQ[1 Mark]
Active strain gauges are connected in a half-bridge configuration to measure strain in a cantilever element. When powered by a voltage source of 10 V, the voltage at the output of the bridge is 1 mV. If the gauge factor is 2.5, the strain in the cantilever element is _____ microstrain.
GATE→2026→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q2
MCQ[1 Mark]
A glass pH electrode behaves linearly with an output change of 60 mV per unit change in pH. The measurement reference is set such that a solution of pH 6 produces an output of 60 mV. The pH of a solution that results in an output of -90 mV is
GATE→2026→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q3
MSQ[1 Mark]
Which of the following statements is/are correct for a thermocouple?
GATE→2026→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q4
MCQ[2 Marks]
A parallel plate capacitive displacement sensor has a plate area of 2 cm22 \text{ cm}^{2}. The air gap between the plates is decreased by 0.1 mm from an initial value of 0.5 mm. The percentage change in the capacitance value is %. (Assume permittivity as ϵ0=8.854×10−12\epsilon_{0} = 8.854 \times 10^{-12} F/m)
GATE→2026→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q5
MCQ[2 Marks]
The emitted radiant energy from a piece of metal was measured using a pyrometer. The temperature was calculated to be 1000∘C1000^{\circ}\text{C} assuming a surface emissivity of 0.8. It was later found that the true surface emissivity was 0.7. The actual temperature of the object is nearest to ∘C^{\circ}\text{C}.
GATE→2026→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q6
NAT[2 Marks]
A current carrying semiconductor of thickness 0.7 mm is placed in a transverse magnetic field. The measured Hall voltage is 0.9 mV and the current is 6 mA. If the Hall coefficient is 4×10−4 m3/C4 \times 10^{-4} \text{ m}^{3}/\text{C}, the value of the incident magnetic field is T. (rounded off to two decimal places)
GATE→2025→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q7
MCQ[1 Mark]
The working of the hand-held metal detector most widely used by security personnel for human frisking is based on the principle of
GATE→2025→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q8
MCQ[1 Mark]
The primary coil of a linear variable differential transformer (LVDT) is supplied with AC voltage as shown in the figure. The secondary coils are connected in series opposition and the output is measured using a true RMS voltmeter. The displacement x of the core is indicated in mm on a linear scale. At the null position x=0x=0 the voltmeter reads 0 V. If the voltmeter reads 0.2 V for a displacement of x=+2x = +2 mm, then for a displacement of x=−3x = -3 mm, the voltmeter reading, in V, is
Figure for Question 8
GATE→2025→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q9
MCQ[1 Mark]
In the force transducer shown in Figure (a), four identical strain gauges S1, S2, S3, and S4 are mounted on a cantilever at equal distance from its base. S1 and S2 are mounted on the top surface and S3 and S4 are mounted on the bottom surface, as shown in the Figure (a). These strain gauges are to be connected to form a Wheatstone bridge consisting of four arms A, B, C, and D, as shown in the Figure (b). From the following options, the correct order to maximize the measurement sensitivity is
Figure for Question 9
GATE→2025→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q10
MCQ[1 Mark]
Match the following sensors with their most suitable applications.
GATE→2025→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q11
NAT[2 Marks]
A metallic strain-gauge (SG) with resistance RSGR_{SG} is connected as shown in the figure... The measured value of tensile strain is ×10−3\times 10^{-3} (rounded off to two decimal places).
Figure for Question 11
GATE→2025→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q12
NAT[2 Marks]
An air filled parallel plate electrostatic actuator is shown in the figure... The magnitude of minimum charge (Q) required to momentarily close the gap between the plates is ×10−14\times 10^{-14} C (rounded off to two decimal places).
Figure for Question 12
GATE→2025→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q13
NAT[2 Marks]
The resistance of a thermistor is measured to be 2.25 k\Omega at 30∘C30^{\circ}\text{C} and 1.17 k\Omega at 60∘C60^{\circ}\text{C}. Its material constant \beta is K (rounded off to two decimal places).
Figure for Question 13
GATE→2024→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q14
MCQ[1 Mark]
The capacitor shown in the figure has parallel plates... If d1d_{1} is decreased by δd1\delta d_{1} the resultant capacitance becomes
Figure for Question 14
GATE→2024→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q15
NAT[1 Mark]
A linear transducer is calibrated for the ranges shown in the figure. The gain of the transducer is mA/∘C^{\circ}\text{C} (rounded off to two decimal places).
Figure for Question 15
GATE→2024→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q16
NAT[1 Mark]
Consider the readout circuit of a piezoelectric sensor shown in the figure... the corresponding change in the voltage VoutV_{out} is V (rounded off to nearest integer).
Figure for Question 16
GATE→2024→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q17
NAT[1 Mark]
A linear potentiometer (0-10 k\Omega) is used to measure the water level... If Vout=5V_{out} = 5 V, the water level is cm (rounded off to one decimal place).
Figure for Question 17
GATE→2024→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q18
NAT[2 Marks]
Consider the capacitive sensor circuit and its output voltage shown in the figure... The frequency of the output voltage V0V_{0} is kHz (rounded off to two decimal places).
Figure for Question 18
GATE→2023→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q19
MCQ[1 Mark]
Which of the following flow meters offers the lowest resistance to the flow?
GATE→2023→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q20
MCQ[1 Mark]
Pair the quantities (p) to (s) with the measuring devices (i) to (iv).
GATE→2023→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q21
NAT[2 Marks]
A wire-wound 'resistive potentiometer type' angle sensor with 72 turns... The output (wiper) voltage when the wiper is on top of both the turns 35 and 36 is V (rounded off to two decimal places).
GATE→2023→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q22
NAT[2 Marks]
The two secondaries of a linear variable differential transformer (LVDT) showed a magnitude of 2 V (RMS)... The output for zero displacement is \mu\text{m} (rounded off to one decimal place).
GATE→2022→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q23
MCQ[1 Mark]
A pneumatic nozzle-flapper system is conventionally used to convert
GATE→2022→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q24
MCQ[1 Mark]
A Hall sensor is based on the principle of
GATE→2022→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q25
MCQ[1 Mark]
The figure shows a Chromel-Alumel thermocouple... When C1 and C2 are held at temperature TCT_{C}, the voltmeter reads a thermal emf E2E_{2}. Then,
Figure for Question 25
GATE→2022→Sensors and Industrial Instrumentation→Sensors and Industrial Instrumentation
Q26
NAT[2 Marks]
Monochromatic light of wavelength 532 nm... The absorption coefficient (in cm−1\text{cm}^{-1}) of the material is (round off to two decimal places).