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 transducers are not linear ?
i. thermistor
ii. thermocouple
iii. IC sensorConsider 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:
Incorrect statements regarding measurement are given :
A. Hot wire anemometer is used to measure displacement
B. Hall effect is used to measure current
C. LVDT is used to measure acceleration and gas flow
D. Piezoelectric Transducer is used to measure acceleration
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:
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.
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 :
The mechanical elements that are used to convert the applied force into a displacement are called :
A device used to convert a non-electrical quantity into an electrical signal is called :
Important Questions from Basics of Transducers
_____ converts mechanical displacement into electrical signals.
Which of the following transducers are not linear ?
i. thermistor
ii. thermocouple
iii. IC sensorConsider 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:
Incorrect statements regarding measurement are given :
A. Hot wire anemometer is used to measure displacement
B. Hall effect is used to measure current
C. LVDT is used to measure acceleration and gas flow
D. Piezoelectric Transducer is used to measure acceleration
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:
