# Pulp & Paper Questions and Answers – Temperature Sensors

This set of Pulp and Paper Multiple Choice Questions and Answers (MCQs) focuses on “Temperature Sensors”.

1. The _________ of metals is a function of temperature and increases with increasing temperature.
a) Coefficient of material
b) Resistance
c) Conductivity
d) Kappa

Explanation: The relationship is fairly linear over a wide temperature range, although second—order transfer functions are often utilized. Resistance temperature detectors often utilize platinum or nickel. The inverse quantity is electrical conductance, and is the ease with which an electric current passes.

2. While using a meter bridge circuit a long signal difference is conditioned which might contain a compensating line to nullify the effect of long leads to the R.T.D.
a) True
b) False

Explanation: This small signal difference is conditioned by utilizing a Wheatstone bridge circuit. A Resistance Temperature Detector is a device which utilized to determine the temperature by measuring the resistance of pure electrical wire. This wire is known as a temperature sensor. If we want to check temperature with high accuracy, R.T.D. is the only one sol. in industries.

3. The _________ of semiconductors is also a function of temperature, but semiconductor materials could be made whose _________ increment drastically with increment temperature
a) Coefficient of material
b) Resistance
c) Conductivity
d) Kappa

Explanation: In intrinsic semiconductor, resistivity decrement with increment temperature The electrons are bumped to the conduction energy band by thermal energy, where they flow freely, and in doing so leave behind holes in the valence band, which also flow freely.

4. Thermocouples consist of a pair of wires made of dissimilar metals joined together at one or more junctions that generate a voltage when subjected to a temperature gradient . This phenomenon is known as the _________
a) Seebeck effect
b) Piezolelectric effect
c) Photovoltaic
d) Photoconductor

Explanation: The linear electromechanical interaction b/w the mechanical and the electrical state in crystalline materials having no inversion symmetry. This effect is a reversible process in that materials exhibiting the direct piezoelectric effect also exhibit the reverse piezoelectric effect.

5. Noise reduction techniques should be utilized to avoid interfering voltages that might be otherwise generated in the system.
a) True
b) False

Explanation: Each input channel is averaged over a programmable period of time to produce 1 measured value. The time is also referred to as integration time. This is extremely helpful at reducing high frequency noise (>1KHz), and could be utilized to reduce power line noise as well by integrating for 1 whole power line cycle.

6. _________ have been utilized in thermostats for years. They are mechanically connected to a switch, such as a mercury switch, to control heaters.
a) Unimetal
b) Bimetallic
c) Trimetallic

Explanation: It’s utilized to convert a temperature change into mechanical displacement. The strip consists of 2 strips of different metals which expand at different rates as they are heated, usually steel and copper, or in some cases steel and brass.

7. What is the name of the question mark area?

a) Measuring junction
b) Bridge junction
c) Temperature junction
d) Compensating junction

Explanation: These are the most widely utilized temperature sensors, because of their simplicity, ruggedness, low cost, wide range and interchangability. The accuracy of temperature measurement with thermocouples is a function of the accuracy of the thermocouple, and not of the data taker.

8. Optical _________ is utilized to measure the temperature of objects. This relies on blackbody radiation.
a) Spectroscopy
b) Pyrometry
c) Geometry
d) Reflection

Explanation: It’s a type of remote-sensing thermometer utilized to measure the temperature of a surface. Various forms of pyrometers have historically existed.

9. In pneumatic systems, one common standard calls for a signal output of _________
a) 10-20 kPa
b) 20-50 kPa
c) 50-100 kPa
d) 20-100 kPa

Explanation: Pneumatic systems utilized extensively in industry are commonly powered by compressed air or inert gases. A centrally located and electrically powered compressor powers cylinders, air motors, and other pneumatic devices.

10. The objective of process control is to keep key process operating parameters within narrow bounds of the ____________
a) Reference value
b) Spot
c) Pith
d) Inception point

Explanation: It’s utilized in industry and enables mass production of consistent products from continuously operated processes such as oil refining, paper manufacturing, chemicals, power plants and many others. It enables automation, by which a small staff of operating personnel could operate a complex process from a central control room.

Sanfoundry Global Education & Learning Series – Pulp and Paper.
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