Which of the following sensors has excellent linearity ?
Si based IC chip
The IC temperature sensor is linear by construction, not by approximation — option 4.
Where its linearity comes from. It does not rely on any bulk material property. Two transistors are run at different current densities, and the difference in their base-emitter voltages is
\(\Delta V_{BE}=\dfrac{kT}{q}\ln\left(\dfrac{J_{1}}{J_{2}}\right)\)
The logarithm is a fixed ratio set by the geometry of the chip, so \(\Delta V_{BE}\) is exactly proportional to absolute temperature — a PTAT voltage. On-chip amplification scales it to a convenient 10 mV/°C, and no linearisation is needed at all.
| Sensor | Law | Linearity |
|---|---|---|
| RTD | \(R_{T}=R_{0}\left(1+\alpha T+\beta T^{2}\right)\) | Good, slightly curved |
| Thermocouple | Polynomial, several terms | Moderate |
| Radiation pyrometer | \(W=\sigma T^{4}\) | Fourth power — the worst |
| Si IC sensor | \(V=10\ \text{mV}/^{\circ}\text{C}\times T\) | Excellent |
Why option 1 is the strong rival. A platinum RTD is the most linear of the classical sensors and is used as an interpolation standard, but the Callendar-Van Dusen equation carries a quadratic term: over 0 to 600 °C the departure from a straight line reaches several degrees, and accurate work must correct for it. "Good" is not "excellent".
Why option 3 is the worst possible answer. A radiation pyrometer measures emitted power, and the Stefan-Boltzmann law makes that vary as the fourth power of absolute temperature. It is the most non-linear device in the list by a wide margin — and it depends on the target's emissivity as well.
What the IC sensor gives up is range. Being a silicon circuit, it works only from about −55 to +150 °C, and cannot approach the RTD's 600 °C, the thermocouple's 1500 °C, or the pyrometer's ability to measure a furnace without touching it. Its virtues are linearity, a large calibrated output that needs no cold-junction compensation or bridge, and a price of a few rupees.
Hence, the sensor with excellent linearity is the Si based IC chip.
Similar Questions
Which of the following statements are correct ?
A. Hygrometer measures the value of humidity directly
B. Hygrometer measures the value of humidity indirectly
C. Wien's bridge is used to measure the frequency of the signal
D. Wien's bridge is used to measure the amplitude of the signal
E. Bimetallic strip is a thermal expansion detector.
Choose the most appropriate answer from the options given below :
Which of the following statements are correct
A. Megnetostrictive transducer operation depends on the change of permeability of magnetic material is when strained.
B. Potentiometer is an active transducer.
C. Turbine flow meters are volumetric flow meters
D. Any metal can be thermistor.
E. Thermocouples are used in high accuracy measurements.
Choose the most appropriate answer from the options given below :
Match List I with List II
LIST I LIST II A. Stroboscope I. Changes its electrical resistance with temperature B. Bolometer II. Generate thermoelectric emf C. Thermocouple III. Changes pressure to displacement D. Diaphragm IV. For measurement of rotary motion Choose the correct answer from the options given below:
Match the following lists :
List – I List – II a. Electromechanical Device i. Seismic Device b. Optical Device ii. Piezo-electric c. Gyroscopic device iii. Interferometers d. Absolute motion device iv. Aerospace vehicle Choose the correct answer from the codes given below:
Consider the following transducers or transducer systems :
(a) Float elements
(b) Seismic system
(c) Gyroscope
Arrange the above transducers/systems in decreasing order of the availability of possible number of output signals.
Consider the following statements associated with electrical and electronic transducers
A. Little power is consumed by transducer
B. Mass intertia effects are not minimized
C. The response time is small
D. Transmission and processing the signal for the purpose of measurement are easier.
Choose the correct answer from the options given below:
Match List I with List II
LIST I LIST II A. Relative error I. The ability of tde device to give identical O/P when repeated measurements are made witd tde same I/P signal B. Precision II. The ratio of difference between measured value and tde true value to tde true value of tde measurand C. Caliberation III. The smallest increment in measure tdat can be detected witd certainity by tde instrument D. Resolution IV. The process of making adjustments or tde scale so tdat tde instrument reading conform to an accepted standard. Choose the correct answer from the options given below:
The fundamental law that is used in temperature measurement is known as
Assertion (A) : Normally, some standard signal conditioner and display devices are used with a transducer, unless they are custom-built to suit the requirements of the transducers.
Reason (R) : A transducer is a device which receives energy in one form and transfer it to a convenient form.
Select your answer using the codes given below :
Which of the following transducers are not linear ?
i. thermistor
ii. thermocouple
iii. IC sensor
Important Questions from Basics of Transducers
Which of the following can act as an inverse transducer?
For transducers, following statements are given:
(A) An optical interferometer is useful for measuring extremely small motions
(B) The damping ratio of a seismic instrument should be low for good dynamic performance
(C) A rate gyro is a relative motion measuring device
(D) A pneumatic motion transducer is non-linear over a wide range of motion
(E) A piezoelectric accelerometer can only be used for static motion measurement
Choose the correct answer from the options given below:
Choose the INCORRECT statement with respect to the use of electrical transducers.
Consider the following transducers:
1. LVDT
2. Piezoelectric
3. Thermocouple
4. Photovoltaic cell
5. Strain gauge
Which of these are active transducers?
Under which condition, Transducers must operate?
