Understanding Temperature and Thermometry

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Questions and Answers

What is the primary property used in a bimetallic strip thermometer?

Color change of liquid crystals

Thermal expansion (correct)

Emission of infrared radiation

Electrical resistance

Which type of thermometer uses a film of heat-sensitive liquid crystal material to measure temperature?

Plastic thermometer (correct)

Mercury thermometer

Pyrometer

Bimetallic strip thermometer

What is the advantage of using infrared thermometers to measure body temperature?

They can measure temperature more quickly than other thermometers

They are more portable than other thermometers

They are less accurate than other thermometers

They are more accurate than other thermometers (correct)

What is the purpose of reference points in temperature scales?

To establish a fixed point of reference for measurement Signup and view all the answers

Which of the following is NOT a common temperature scale?

Newton scale Signup and view all the answers

What is the principle behind the operation of a pyrometer?

Emission of infrared radiation that varies with temperature Signup and view all the answers

What is the advantage of using a bimetallic strip thermometer over an alcohol thermometer?

It is more accurate Signup and view all the answers

Which type of thermometer is commonly used to measure body temperature in the ear canal?

Infrared thermometer Signup and view all the answers

Why does the wood on a porch feel warmer than the metal of a bike on a cold winter morning?

The wood has a lower thermal conductivity than the metal Signup and view all the answers

What is the main reason why people feel hotter on hot, humid days than on hot, dry days?

Sweat does not evaporate from the skin as efficiently on humid days Signup and view all the answers

What is the definition of temperature based on?

What we measure with a thermometer Signup and view all the answers

Why can different physical properties be used as the basis of thermometers?

Because they all respond to temperature in a reproducible way Signup and view all the answers

What happens to the volume of most substances as temperature increases?

It increases Signup and view all the answers

What would two accurate thermometers show when placed in hot water and cold water, respectively?

The hot water has a higher temperature than the cold water Signup and view all the answers

Why do people perceive the tepid water as cool to the hand that was in hot water and warm to the hand that was in cold water?

Because the perception of temperature is relative to the previous stimulus Signup and view all the answers

What is NOT a factor that affects our perception of temperature?

Color of the surroundings Signup and view all the answers

In the laboratory, what is the lowest temperature that has been achieved?

4.5 × 10−10 K Signup and view all the answers

What is the coldest recorded place on Earth's surface?

Vostok, Antarctica Signup and view all the answers

At what temperature do the pressures of gases extrapolate to zero?

–273.15ºC Signup and view all the answers

What is the primary assumption behind the concept of absolute zero?

All molecular motion will eventually cease Signup and view all the answers

What is the purpose of the zeroth law of thermodynamics?

To ensure thermal equilibrium between systems Signup and view all the answers

What is the significance of the logarithmic scale in Figure 6?

It shows the tremendous range of temperatures in nature Signup and view all the answers

Why can't thermometers measure the temperature of an object directly?

Because they take their own temperature Signup and view all the answers

What is the ultimate limit of temperature that can be achieved?

Absolute zero, but it cannot be reached Signup and view all the answers

What is the primary condition for two bodies to be in thermal equilibrium?

They must have the same temperature Signup and view all the answers

What is the fundamental principle behind the zeroth law of thermodynamics?

Two systems in thermal equilibrium with a third system are also in thermal equilibrium with each other Signup and view all the answers

What is the significance of the zeroth law of thermodynamics?

It is a fundamental principle that underlies all of thermodynamics Signup and view all the answers

Why is the temperature of a thermometer in thermal equilibrium with a system an accurate measure of the system's temperature?

Because the thermometer is in thermal equilibrium with the system Signup and view all the answers

What can be inferred about two systems that are in thermal equilibrium with each other?

They have the same temperature Signup and view all the answers

What is an example of the zeroth law of thermodynamics in action?

A baby in an incubator Signup and view all the answers

What is the significance of the fact that the temperature of a system does not depend on its size?

It means that the temperature of a system is an intensive property Signup and view all the answers

When will heat stop flowing between two systems?

When they reach the same temperature Signup and view all the answers

What is the freezing point of water on the Reaumur temperature scale?

0ºR Signup and view all the answers

What is the boiling point of water on the Celsius temperature scale?

100ºC Signup and view all the answers

What is the conversion equation from Celsius to Reaumur scale?

TºR = 0.8ºR/ºC × TºC Signup and view all the answers

What is the normal body temperature in Fahrenheit?

98.6ºF Signup and view all the answers

What is the temperature range in which human beings can survive?

24ºC to 44ºC Signup and view all the answers

What is the conversion equation from Celsius to Fahrenheit?

TºF = 9/5 TºC + 32 Signup and view all the answers

What is the room temperature on the Celsius scale?

25ºC Signup and view all the answers

What is the room temperature on the Kelvin scale?

298 K Signup and view all the answers

Study Notes

Temperature and Thermometry

Temperature is operationally defined as what we measure with a thermometer
Two accurate thermometers, one placed in hot water and the other in cold water, will show the hot water to have a higher temperature
Temperature is the quantity measured by a thermometer, independent of our senses of hot and cold

Misconceptions about Temperature

Human perception of temperature is not determined by temperature alone, but also by other factors such as humidity and heat conduction
On a cold winter morning, the wood on a porch may feel warmer than the metal of a bike, even though they are at the same temperature, because of the difference in heat conduction

Thermometers and Temperature Measurement

Any physical property that depends on temperature and whose response to temperature is reproducible can be used as the basis of a thermometer
Examples of thermometers include:
- Volume-based thermometers (e.g. alcohol thermometer, mercury thermometer, bimetallic strip)
- Electrical resistance thermometers (e.g. plastic thermometer)
- Infrared radiation thermometers (e.g. pyrometer)
Temperature scales are used to measure temperature, with well-defined reference points for comparison
The three most common temperature scales are the Fahrenheit, Celsius, and Kelvin scales

Temperature Scales and Conversions

The Celsius scale is defined such that the freezing point of water is 0°C and the boiling point is 100°C
The Fahrenheit scale is defined such that the freezing point of water is 32°F and the boiling point is 212°F
The Kelvin scale is defined such that the freezing point of water is 273.15 K and the boiling point is 373.15 K
Conversion equations exist between these scales, allowing for easy conversion between temperatures

Temperature Ranges in the Universe

Human body temperature can vary from 24°C to 44°C (75°F to 111°F), with an average normal body temperature of 37.0°C (98.6°F)
The lowest temperatures ever recorded are around 4.5 × 10^-10 K, achieved in laboratory experiments
The coldest recorded place on Earth's surface is Vostok, Antarctica at -89°C (183 K), and the coldest place in the universe is the Boomerang Nebula at 1 K

Absolute Zero and the Zeroth Law of Thermodynamics

Absolute zero is the temperature at which all molecular motion has ceased, defined as -273.15°C or 0 K
The zeroth law of thermodynamics states that if two systems, A and B, are in thermal equilibrium with each other, and B is in thermal equilibrium with a third system C, then A is also in thermal equilibrium with C
This law is the basis for thermal equilibrium and allows for the measurement of temperature using thermometers

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Description

Learn about the operational definition of temperature, how thermometers work, and common misconceptions about temperature. Discover how factors like humidity affect our perception of temperature.