This set of Engineering Materials & Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Thermometry and the Types of Thermometers”.
1. Measurement of elevated temperatures is defined as ___________
Explanation: Pyrometry deals with elevated temperatures, generally around 950 F. The apparatus that is used in this process is known as a pyrometer. Thermometry generally deals with the measurement of temperatures below 950 F.
2. What temperature does the dark red color generally deal with?
a) 950 F
b) 1150 F
c) 1175 F
d) 1300 F
Explanation: Temperature of metals can be estimated by simply looking at the color of the hot body. Dark red is assigned a temperature of 1150 F, whereas for faint red, dark cherry, and cherry red it is 950 F, 1175 F, and 1300 F in that order.
3. What temperature is the dark orange color associated with?
a) 1475 F
b) 1650 F
c) 1750 F
d) 1800 F
Explanation: Temperature of metals can be estimated by simply looking at the color of the hot body. Dark orange is associated with a temperature of about 1150 F, while for bright cherry, orange, and yellow it is 1475 F, 1750 F, and 1800 F correspondingly.
4. Bimetallic strips are employed in ________ thermometers.
Explanation: Bimetallic strips made by bonding of high-expansion and low-expansion metals are used in the common thermostat. When used as an industrial temperature indicator, these can be bent into a coil.
5. Bimetallic strips contain _______ as a metal.
a) Muntz metal
b) Yellow brass
Explanation: Bimetallic strips include invar as one metal and yellow brass as another. For higher temperatures, nickel alloy can be used. These can be used in temperatures ranging from -100 F to 1000 F.
6. Why is invar used in bimetallic strips?
a) Low density
b) Low coefficient of expansion
c) High-temperature resistance
d) High abrasion resistance
Explanation: Most bimetallic strips are composed of invar and yellow brass as metal. Invar has the advantage of low coefficient of expansion, whereas yellow brass has the ability to be used at low temperatures.
7. _______ is commonly used in liquid-expansion thermometers.
a) Bourdon tube
b) Spinning rotor gauge
c) McLeod gauge
Explanation: Liquid-expansion thermometers consist of a bulb and an expansible device. The bulb is exposed to the temperature that needs to be measured and usually, a Bourdon tube is used as an expansion device. These are connected by capillary tubing and are filled with a medium.
8. Resistance thermometer generally makes use of ________ for measurement of resistance.
c) Diode bridge
d) Wheatstone bridge
Explanation: Resistance thermometers are based on the principle of increase in electrical resistance with increasing temperature. It consists of a resistance coil mounted in a protecting tube which is connected to a resistance measuring instrument. Generally, Wheatstone bridge is used in this process.
9. Which of these materials is not used for resistance coils?
Explanation: Resistance coils are generally made of nickel, copper, or platinum. Nickel and copper can be used in the temperature range of 150-500 F, whereas platinum can be used between -350 to 1100 F.
10. Liquid expansion thermometers are filled with ________
Explanation: The liquid-expansion thermometer has the entire system filled with an organic liquid or mercury. Mercury is used at a temperature range of -35 to 950 F. Alcohol and creosote are used at -110 to 160 F, and 20 to 400 F respectively.
Sanfoundry Global Education & Learning Series – Engineering Materials & Metallurgy.
To practice all areas of Engineering Materials & Metallurgy, here is complete set of 1000+ Multiple Choice Questions and Answers.