Thermometry MCQs

Question 1

Thermometer used to measure very low temperature is

Accepted Answer

Magnetic thermometer

Answer

Thermocouple

Answer

Pyrometer

Answer

Gas thermometer

Question 2

The absolute zero is the temperature at which:

Accepted Answer

molecular motion stops

Answer

water freezes

Answer

substances exist in solid state

Answer

none of these happens

Question 3

If two temperature scales are dipped in a hot bath and the reading in Fahrenheit scale is 3 times the Celsius scale, the temperature of the hot bath is:

Accepted Answer

80/3°C

Answer

100°C

Answer

50°C

Answer

50/3°C

Question 4

A thermometer reads $140^\circ\mathrm{F}$. What is the corresponding temperature on the Celsius scale?

Accepted Answer

$60^\circ\mathrm{C}$

Answer

$140^\circ\mathrm{C}$

Answer

$95.6^\circ\mathrm{C}$

Answer

$75^\circ\mathrm{C}$

Question 5

Express $-50^\circ\mathrm{C}$ on the Kelvin scale.

Accepted Answer

$223\,\mathrm{K}$

Answer

$323\,\mathrm{K}$

Answer

$23\,\mathrm{K}$

Answer

$-50\,\mathrm{K}$

Question 6

A faulty thermometer reads $1^\circ\mathrm{C}$ at the ice point and $99^\circ\mathrm{C}$ at the steam point. What is the actual temperature when it reads $25^\circ\mathrm{C}$?

Accepted Answer

$24.49^\circ\mathrm{C}$

Answer

$25.34^\circ\mathrm{C}$

Answer

$36.3^\circ\mathrm{C}$

Answer

$22.3^\circ\mathrm{C}$

Question 7

A faulty thermometer indicates $5^\circ\mathrm{C}$ at the lower fixed point and $95^\circ\mathrm{C}$ at the upper fixed point. Find the actual temperature when it reads $35^\circ\mathrm{C}$.

Accepted Answer

$33.3^\circ\mathrm{C}$

Answer

$60^\circ\mathrm{C}$

Answer

$40^\circ\mathrm{C}$

Answer

$20.5^\circ\mathrm{C}$

Question 8

For a constant-volume gas thermometer, the gas should ideally be at:

Accepted Answer

High temperature and low pressure

Answer

High pressure and low temperature

Answer

Low temperature and low pressure

Answer

High temperature and high pressure

Question 9

Convert $98.4^\circ\mathrm F$ into Celsius.

Accepted Answer

$36.9^\circ\mathrm C$

Answer

$39^\circ\mathrm C$

Answer

$98.4^\circ\mathrm C$

Answer

$371.4^\circ\mathrm C$

Question 10

Which of the following best represents the approximate temperature range permitted by liquid mercury in an ordinary mercury-in-glass thermometer?

Accepted Answer

$-30^\circ\mathrm C$ to $357^\circ\mathrm C$

Answer

$-30^\circ\mathrm C$ to $100^\circ\mathrm C$

Answer

$0^\circ\mathrm C$ to $200^\circ\mathrm C$

Answer

$-30^\circ\mathrm C$ to $200^\circ\mathrm C$

Question 11

What is $40^\circ\mathrm C$ in Fahrenheit?

Accepted Answer

$104^\circ\mathrm F$

Answer

$102^\circ\mathrm F$

Answer

$106^\circ\mathrm F$

Answer

$108^\circ\mathrm F$

Question 12

What is the exact Celsius value of absolute zero?

Accepted Answer

$-273.15^\circ\mathrm C$

Answer

$-273\,\mathrm K$

Answer

$-273.14^\circ\mathrm C$

Answer

$-273.16^\circ\mathrm C$

Question 13

Hailstones are formed mainly by:

Accepted Answer

Freezing and growth of supercooled water droplets in thunderstorm clouds

Answer

Freezing of an entire cloud

Answer

Direct freezing of water vapour without a liquid phase

Answer

None of the above

Question 14

Approximately what is the maximum temperature measurable by an ordinary mercury-in-glass thermometer at atmospheric pressure?

Accepted Answer

$360^\circ\mathrm C$

Answer

$100^\circ\mathrm C$

Answer

$260^\circ\mathrm C$

Answer

$500^\circ\mathrm C$

Question 15

Convert $69.8^\circ\mathrm F$ to Celsius.

Accepted Answer

$21^\circ\mathrm C$

Answer

$45^\circ\mathrm C$

Answer

$40^\circ\mathrm C$

Answer

$54^\circ\mathrm C$

Question 16

At what temperature do the Celsius and Fahrenheit scales have the same numerical reading?

Accepted Answer

$-40^\circ\mathrm C$

Answer

$40^\circ\mathrm C$

Answer

$40^\circ\mathrm{Re}$

Answer

$40^\circ\mathrm F$

Question 17

At a certain temperature, the Fahrenheit reading is three times the Celsius reading. Find the Celsius temperature.

Accepted Answer

$\frac{80}{3}^\circ\mathrm C$

Answer

$100^\circ\mathrm C$

Answer

$80^\circ\mathrm C$

Answer

$70^\circ\mathrm C$

Question 18

Which temperature scale has no negative thermodynamic temperatures for ordinary equilibrium systems?

Accepted Answer

Kelvin

Answer

Celsius

Answer

Fahrenheit

Answer

Réaumur

Question 19

A temperature falls from $212^\circ\mathrm F$ to $140^\circ\mathrm F$. How large is the fall in Celsius degrees?

Accepted Answer

$40^\circ\mathrm C$

Answer

$25^\circ\mathrm C$

Answer

$30^\circ\mathrm C$

Answer

$35^\circ\mathrm C$

Question 20

The mercury thread is $40\,\mathrm{mm}$ above the lower fixed point of a Fahrenheit thermometer, and the distance between its fixed points is $160\,\mathrm{mm}$. Find its reading.

Accepted Answer

$77^\circ\mathrm F$

Answer

$45^\circ\mathrm F$

Answer

$57^\circ\mathrm F$

Answer

$68^\circ\mathrm F$

Question 21

A constant-volume gas thermometer shows gas pressures of $50\,\mathrm{cmHg}$ at $0^\circ\mathrm C$ and $90\,\mathrm{cmHg}$ at $100^\circ\mathrm C$. Find the temperature when the pressure is $60\,\mathrm{cmHg}$, assuming linear calibration.

Accepted Answer

$25^\circ\mathrm C$

Answer

$12^\circ\mathrm C$

Answer

$12.5^\circ\mathrm C$

Answer

$40^\circ\mathrm C$

Question 22

The resistance of a thermometer is $2.71\,\Omega$ at $10^\circ\mathrm C$ and $3.70\,\Omega$ at $100^\circ\mathrm C$. Assuming a linear resistance–temperature relation, find the temperature when the resistance is $3.26\,\Omega$.

Accepted Answer

$60^\circ\mathrm C$

Answer

$40^\circ\mathrm C$

Answer

$50^\circ\mathrm C$

Answer

$70^\circ\mathrm C$

Question 23

A resistance thermometer has resistance $1\,\Omega$ at $300\,\mathrm K$. If its temperature coefficient of resistance at $300\,\mathrm K$ is $\alpha=0.00125\,\mathrm{K^{-1}}$, at what temperature will its resistance become $2\,\Omega$, assuming linear variation?

Accepted Answer

$1100\,\mathrm K$

Answer

$1154\,\mathrm K$

Answer

$1400\,\mathrm K$

Answer

$1127\,\mathrm K$

Question 24

A faulty Celsius thermometer reads $50^\circ\mathrm C$ at the true ice point and $95^\circ\mathrm C$ at the true steam point. What is the actual temperature when it reads $59^\circ\mathrm C$?

Accepted Answer

$20^\circ\mathrm C$

Answer

$59^\circ\mathrm C$

Answer

$60^\circ\mathrm C$

Answer

$58^\circ\mathrm C$

Question 25

Thermometer X reads $15^\circ$ and $75^\circ$ at the ice and steam points, respectively. Thermometer Y reads $25^\circ$ and $125^\circ$ at those points. What does Y read when X reads $60^\circ$?

Accepted Answer

$100^\circ$

Answer

$75^\circ$

Answer

$80^\circ$

Answer

$90^\circ$

Question 26

A faulty thermometer reads $-10^\circ\mathrm C$ at the true ice point and $60^\circ\mathrm C$ at a true temperature of $50^\circ\mathrm C$. What will it read at the true steam point?

Accepted Answer

$130^\circ\mathrm C$

Answer

$90^\circ\mathrm C$

Answer

$110^\circ\mathrm C$

Answer

$125^\circ\mathrm C$

Question 27

A thermocouple has a sensitivity of $40\,\mu\mathrm{V}/^\circ\mathrm C$ and is connected to a galvanometer of resistance $10\,\Omega$ that can detect a minimum current of $1\,\mu\mathrm A$. Neglecting other resistances, what is the smallest detectable temperature difference?

Accepted Answer

$0.25^\circ\mathrm C$

Answer

$0.15^\circ\mathrm C$

Answer

$0.20^\circ\mathrm C$

Answer

$0.40^\circ\mathrm C$

Question 28

The resistance of a thermometer is $6.74\,\Omega$ at $0^\circ\mathrm C$ and $7.74\,\Omega$ at $100^\circ\mathrm C$. Assuming linear variation, what is its resistance at $50^\circ\mathrm C$?

Accepted Answer

$7.24\,\Omega$

Answer

$7.56\,\Omega$

Answer

$7.64\,\Omega$

Answer

$7.52\,\Omega$

Term	Meaning
Thermometry	Measurement of temperature
Thermometer	Device used to measure temperature of a body
Principle	Thermal equilibrium
Thermometric property	Measurable property sensitive to temperature change
Examples of thermometric properties	Volume, pressure, resistance, thermoelectric emf, radiation intensity, magnetic susceptibility

Feature	Heat	Temperature
Meaning	Form of energy	Degree of hotness or coldness
Molecular basis	Total sum of kinetic energy	Average translational kinetic energy
Depends on mass	Yes	No
Flow	Flows due to temperature difference	Does not flow
Origin	Molecular vibration	Thermal state of body

Term	Meaning
Cryogenics	Production and measurement of very low temperature below 77 K
Pyrometry	Production and measurement of very high temperature above 1000 K

Type	Examples / Points
Solid thermometers	Platinum resistance thermometer, radiation pyrometer, magnetic thermometer, thermoelectric thermometer
Liquid thermometers	Mercury thermometer, alcohol thermometer
Gas thermometers	Constant volume gas thermometer, constant pressure gas thermometer, vapour pressure thermometer

Scale	Symbol	LFP	UFP	No. of divisions
Celsius	°C	0°C	100°C	100
Fahrenheit	°F	32°F	212°F	180
Kelvin	K	273.15 K	373.15 K	100
Reaumur	°R	0°R	80°R	80
Rankine	°Rn	492°Rn	672°Rn	180

16Thermometry

Table 1: Thermometry Basics

Table 1: Heat vs Temperature

Table 1: Temperature Ranges

Table 1: Thermometer Classification

Table 1: Common Temperature Scales

Table 1: Thermometers: Principle, Formula and Range

Table 1: Platinum Resistance Thermometer

Table 1: Thermoelectric Thermometer

Table 1: Total Radiation Pyrometer

Table 1: Special Thermometers

Table 1: Common Temperature Readings

Table 1: Important Thermometry Points

Table 1: Thermometry One-Liners

More CEE preparation resources

Thermometer	Thermometric substance	Measurable quantity	Principle	Formula	Range
Mercury thermometer	Mercury	Change in volume/length	Thermal expansion of liquid		-35°C to 357°C
Alcohol thermometer	Alcohol	Change in length	Thermal expansion of liquid		-110°C to 76°C
Constant volume gas thermometer	Hydrogen / helium / nitrogen	Pressure			-268°C to 1500°C
Constant pressure gas thermometer	Gas	Volume			-268°C to 500°C
Platinum resistance thermometer	Platinum	Resistance	Resistance of metal varies with temperature / Wheatstone bridge		-200°C to 1200°C
Thermoelectric thermometer	Thermocouple	Thermo-emf	Seebeck effect	\(e=At+Bt^2\)	-200°C to 1600°C
Total radiation pyrometer	Radiating body	Intensity of radiation	Stefan's law	\(E=\sigma T^4\)	800°C to 4000°C
Vapour pressure thermometer	Liquid vapour / helium	Saturated vapour pressure	Vapour pressure depends on temperature	\(\log P=a+bT+\frac{c}{T}\)	0.71 K to 122 K
Magnetic thermometer	Ferromagnetic substance	Magnetic susceptibility \((\chi)\)	Curie's law: \(\chi\propto\frac{1}{T}\)	—	Below 1 K

Point	Description
Principle	Resistance of metal changes with temperature
Formula	\(R_t=R_0(1+\alpha t)\)
Temperature coefficient	High and positive
Accuracy	Most accurate thermometer of lower range except gas thermometer
Use	Measures temperature inside motor engine

Point	Description
Thermometric substance	Thermocouple
Principle	Seebeck effect
Thermometric quantity	Thermo-emf
Formula	\(e=At+Bt^2\)
Use	Rapidly changing temperature

Thermometer	Use
Six's thermometer	Measures minimum and maximum temperature simultaneously
Beckmann's thermometer	Measures boiling point / small temperature difference accurately
Magnetic thermometer	Measures temperature below 1 K
Radiation pyrometer	Measures very high temperature

Scales	Common reading
Celsius and Fahrenheit	-40°
Celsius and Reaumur	0°
Fahrenheit and Reaumur	-25.6°
Celsius and Kelvin	Never common
Fahrenheit and Rankine	Never common

Fact	Answer
Celsius-Fahrenheit common reading	\(-40^\circ C=-40^\circ F\)
Celsius-Reaumur common reading	\(0^\circ C=0^\circ R\)
Fahrenheit-Reaumur common reading	\(-25.6^\circ F=-25.6^\circ R\)
Kelvin scale	No negative temperature
Absolute zero	\(0K=-273.15^\circ C\)
Most accurate temperature measurement	Constant volume gas thermometer
Gas thermometer	Standard thermometer
Mercury thermometer upper limit	357°C
Mercury thermometer with high-pressure nitrogen	Can measure up to about 500°C
Alcohol thermometer sensitivity	More sensitive than mercury
Alcohol expansion	About 7 times mercury
Hydrogen above 500°C	Cannot be used because it diffuses
Six's thermometer	Maximum and minimum temperature
Beckmann's thermometer	Boiling point / small temperature difference