GATE IN Sensors and Industrial Instrumentation PYQs & Answers — Page 4

Questions 31–40 of 53. Imported answers require independent review unless marked reviewed.

For the full bridge made of linear strain gages with gage factor 2 as shown in the diagram,

at 0 °C and strain is 0. The temperature coefficient of resistance of the strain gages used is 0.005 per °C. All strain gages are made of same material and exposed to same temperature. While measuring a strain of 0.01 at a temperature of 50 °C, the output

in millivolt is _____ (rounded off to two decimal places).

Diagram for Instrumentation Engineering question 53

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is the current flowing through a Hall effect sensor and

is the magnetic flux density perpendicular to the direction of the current (in the plane of the Hall effect sensor), the Hall voltage generated is ____.

Your answerChoose one option.

Directly proportional to

and inversely proportional to

Directly proportional to both

and

Inversely proportional to both

and

Inversely proportional to

and directly proportional to

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The capacitance

of a capacitive type sensor is

pF, where

is the input to the sensor. As shown in the figure, the sensor is excited by a voltage

V. The other terminal of the sensor is tied to the input of a high input impedance amplifier through a shielded cable, with shield connected to ground. The cable capacitance is 100 pF. The peak of the voltage

at the input of the amplifier when

(in volts) is ____.

Diagram for Instrumentation Engineering question 24

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The circuit shown uses ideal opamp powered from a supply

V. If the charge

generated by the piezoelectric sensor is of the form

μC, the peak detector output after 10 cycles of

(in volts, rounded off to one decimal place) is ____

Diagram for Instrumentation Engineering question 44

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A metallic strain gauge of resistance

with a gauge factor of 2 is bonded to a structure made of a metal with modulus of elasticity of 200 GN/m

. The value of

is 1 kΩ when no stress is applied.

is a part of a quarter bridge with three identical fixed resistors of 1 kΩ each. The bridge is excited from a DC voltage of 4 V. The structure is subjected to a stress of 100 MN/m

. Magnitude of the output of the bridge (in mV, rounded off to two decimal places) is ____

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The mutual inductances between the primary coil and the secondary coils of a linear variable differential transformer (LVDT) shown in the figure are

and

. Assume that the self-inductances

and

remain constant and are independent of

. When

is in the range ±10 mm,

and

change linearly with

. At

mm or −10 mm, the change in the magnitudes of

and

is 0.25

. For a particular displacement

, the voltage across the detector becomes zero when

. The value of

(in mm, rounded off to one decimal place) is ____

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Thermocouples measure temperature based on

Your answerChoose one option.

Photoelectric effect

Seebeck effect

Hall effect

Thermal expansion

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A pitot-static tube is used to estimate the velocity of an incompressible fluid of density 1 kg/m³. If the pressure difference measured by the tube is 200 N/m², the velocity of the fluid, assuming the pitot-tube coefficient to be 1.0, is ______ m/s.

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A differential capacitive sensor with a distance between the extreme plates 100 mm is shown in figure below. The difference voltage

, where

and

are the rms values, for a downward displacement of 10 mm of the intermediate plate from the central position, in volts, is

Diagram for Instrumentation Engineering question 37

Your answerChoose one option.

0.9

1.0

1.1

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A piezoelectric transducer with sensitivity of 30 mV/kPa is intended to be used in the range of 0 kPa to 100 kPa. The readout circuit has a peak noise amplitude of 0.3 mV and measured signals over the full pressure range are encoded with 10 bits. The smallest pressure that produces a non-zero output, in units of Pa, is approximately

Your answerChoose one option.

100

240

300

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GATE IN Sensors and Industrial Instrumentation PYQs

Question 53

Question 10

Question 24

Question 44

Question 45

Question 53

Question 13

Question 24

Question 37

Question 38