Temperature Measurement and Scales Quiz

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Questions and Answers

What does temperature measure in a body?

The volume occupied by the body

The thermal energy in a body (correct)

The density of the material

The pressure exerted by the molecules

Which temperature scale was the first to gain acceptance?

Kelvin

Fahrenheit (correct)

Celsius

Rankine

At what temperature does molecular motion cease?

0° Kelvin

32° Fahrenheit

100° Celsius

Absolute zero (correct)

What are the two reference points of the Fahrenheit scale?

Freezing point of a salt solution and internal temperature of oxen Signup and view all the answers

Which temperature scale is based on absolute zero?

Kelvin Signup and view all the answers

What is the boiling point of pure water at 1 atm in Fahrenheit scale?

212° Signup and view all the answers

Why is precise temperature measurement important in industrial processes?

It is related to physical parameters and chemical reactions. Signup and view all the answers

Which of the following is NOT a temperature scale mentioned?

Newton Signup and view all the answers

What is the primary mechanism of heat transfer that involves molecular vibration within a material?

Conduction Signup and view all the answers

Which type of convection occurs when the motion of particles is solely due to density differences caused by temperature?

Natural convection Signup and view all the answers

How is thermal conductivity of a material typically measured?

In BTUs per hour per foot per °F Signup and view all the answers

What is the term for the change in dimensions of a material due to temperature alteration?

Thermal expansion Signup and view all the answers

What type of heat transfer involves electromagnetic waves and can occur through a vacuum?

Radiation Signup and view all the answers

What is the coefficient of thermal expansion expressed in terms of?

Change in linear dimension per degree temperature change Signup and view all the answers

When is heat considered extracted, based on the heat transfer equation?

With a negative answer Signup and view all the answers

How are the thermal expansion coefficients for materials expressed?

Per degree temperature change for linear dimensions Signup and view all the answers

What is the primary method by which heat convection is influenced?

Density and viscosity of the material Signup and view all the answers

Which of the following is NOT a method of measuring temperature?

Infrared radiation calibration Signup and view all the answers

What factor contributes to the difficulty in choosing the correct value for 'h' in heat convection calculations?

The array of influencing variables Signup and view all the answers

What is a significant advantage of mercury in glass thermometers?

Mercury expands more than glass in response to temperature changes Signup and view all the answers

Which of the following is true regarding linear and volume expansion in materials?

Linear expansion measures change in length, while volume expansion measures change in volume Signup and view all the answers

What is one of the technological advancements that led to the decline of mercury thermometers?

Advent of digital thermometers Signup and view all the answers

What key property enables mercury to travel up the glass tube in a thermometer?

High coefficient of expansion compared to glass Signup and view all the answers

What characteristic does heat radiation depend on?

Surface color, texture, and shapes involved Signup and view all the answers

What principle do mercury and alcohol thermometers rely on to measure temperature?

Liquid expansion and contraction Signup and view all the answers

Which type of thermometer is best suited for non-contact temperature readings?

Infrared (IR) thermometers Signup and view all the answers

Which application is a common use for thermocouple thermometers?

Industrial high-temperature monitoring Signup and view all the answers

What is the main working component of a digital thermometer?

Thermistor or resistance temperature detector Signup and view all the answers

What is a significant advantage of using liquid glass thermometers over mercury thermometers?

Wider operating temperature range Signup and view all the answers

How does an infrared thermometer convert temperature readings?

By detecting emitted infrared radiation Signup and view all the answers

What type of thermometer typically displays temperature readings in a digital format?

Digital thermometers Signup and view all the answers

What is the primary reason for the use of non-toxic liquids in liquid glass thermometers?

To eliminate health hazards Signup and view all the answers

What is the main characteristic of NTC thermistors?

Their resistance decreases as temperature increases. Signup and view all the answers

In which application are PTC thermistors most commonly used?

Overcurrent protection circuits. Signup and view all the answers

What principle do thermocouples operate on?

The generation of voltage through the Seebeck effect. Signup and view all the answers

What does the 'hot' junction of a thermocouple refer to?

The point where the two dissimilar metals are joined. Signup and view all the answers

Which of the following best describes the temperature range capabilities of thermocouples?

They can measure from around -200°C to 2000°C depending on materials. Signup and view all the answers

What is a common use of thermistors in battery chargers?

To monitor and protect against overheating. Signup and view all the answers

How does the resistance of a PTC thermistor change when the current through it becomes too high?

The resistance increases dramatically. Signup and view all the answers

Which is NOT a characteristic feature of thermistors?

Ability to measure very high temperatures. Signup and view all the answers

What is a common temperature range for silicon-based semiconductor sensors?

-50°C to +150°C Signup and view all the answers

Which of the following is NOT a common application of semiconductor temperature sensors?

Nuclear Reactor Monitoring Signup and view all the answers

What is a major disadvantage of semiconductor temperature sensors compared to thermocouples and RTDs?

Limited temperature range Signup and view all the answers

Which semiconductor temperature sensor offers a voltage output proportional to temperature?

LM35 Signup and view all the answers

In which system are semiconductor sensors frequently used for managing the temperature of batteries?

Battery Management Systems Signup and view all the answers

What can affect the accuracy of semiconductor temperature sensors?

Supply voltage and circuit noise Signup and view all the answers

Which feature does the TMP36 sensor provide?

High accuracy with a linear digital output Signup and view all the answers

Why are semiconductor temperature sensors considered suitable for electronic systems?

They are versatile, inexpensive, and compact. Signup and view all the answers

Study Notes

Chapter 5: Temperature and Heat

This chapter discusses the difference between temperature and heat, units of measurement, thermal time constants, and common methods for measuring temperature and heat.

Chapter Objectives

The difference between temperature and heat
Various temperature scales (Fahrenheit, Celsius, Rankine, Kelvin)
Temperature and heat formulas
Heat transfer mechanisms (conduction, convection, radiation)
Specific heat capacity and heat energy
Coefficients of linear and volumetric expansion
Temperature measuring devices
Introduction to thermal time constants

Introduction

Temperature control is essential in many industrial and chemical processes, as various physical parameters and chemical reactions depend on temperature.
Accurate measurement of temperature is necessary for precise control.

Basic Terms

Temperature is a measure of thermal energy, reflecting the relative hotness or coldness of a medium.
Temperature is measured using scales like Fahrenheit (°F), Celsius (°C), Rankine (°R), or Kelvin (K).
Absolute zero is the temperature at which molecular motion ceases, and the energy of the molecules is zero.

Fahrenheit Scale

Proposed in the early 1700s by Fahrenheit.
Uses the freezing point of a concentrated salt solution and the internal temperature of oxen as reference points (0° and 100°).
The 180-degree range is used for the freezing and boiling points of water.
Temperature of freezing point and boiling point of water change with pressure.

Celsius/Centigrade Scale

Proposed in the mid-1700s by Celsius.
Uses the freezing point and boiling point of pure water at 1 atm as reference points (0° and 100°).

Rankine Scale

Proposed in the mid-1800s by Rankine.
Based on the Fahrenheit scale, with a 1°F change equivalent to a 1°R change.
The freezing and boiling points of water are 491.6°R and 671.6°R, respectively, at 1 atm.

Kelvin Scale

Proposed in the late 1800s by Lord Kelvin.
Based on absolute zero and the Celsius scale, with a 1°C change equivalent to a 1 K change.
The freezing and boiling points of water are 273.15 K and 373.15 K, respectively, at 1 atm.

Heat Definitions

Heat is a form of energy.
As energy is supplied to a system, the vibration amplitude of molecules and the temperature increases.
A British Thermal Unit (BTU) is the amount of energy required to raise the temperature of 1 lb of pure water by 1°F at 68°F and atmospheric pressure.
A calorie is the amount of energy required to raise the temperature of 1 gram of pure water by 1°C at 4°C and atmospheric pressure.
Joules (SI) are also used to define heat energy.

Specific Heat

Specific heat is the quantity of heat energy needed to raise the temperature of a given weight of material by 1°.
BTUs in the English system (1 BTU is the heat needed to raise 1 lb of material by 1°F)
Calories in the SI system (1 calorie is the heat needed to raise 1 g of material by 1°C).

Heat Transfer

Mechanisms of heat transfer include: conduction, convection, and radiation.
Conduction: heat transfer through a material.
Convection: heat transfer due to motion of elevated-temperature particles.
Radiation: emission of energy by electromagnetic waves.

Thermal Expansion

Linear thermal expansion: Change in dimensions of a material due to temperature changes.
Volume thermal expansion: Change in volume of a material due to changes in temperature.

Temperature and Heat Formulas

Formulas for converting between different temperature scales are provided.
Formula for calculating the amount of heat needed to raise or lower the temperature of a given weight of a body.
Formula for heat conduction through a material.

Temperature Measuring Devices

There are various methods for measuring temperature:
- Expansion mechanisms for dimensional changes
- Electrical resistance change
- Semiconductor characteristic changes
- Voltage generated by dissimilar metals
- Radiant energy
Specific devices like thermometers based on liquid expansion, digital thermometers, thermocouples, pressure-spring thermometers, and resistance temperature devices are discussed.

Thermometers

Mercury in glass thermometer.
Liquid in glass thermometers.
Digital thermometers.
Thermocouples.
Bimetallic strip thermometers.
Pressure-spring thermometers.

Semiconductor Temperature Sensors

Types of thermistors (NTC, PTC).
Diode-based temperature sensing.
Silicon-based temperature sensors.
Features and advantages of these temperature sensors.

Thermal Time Constant

Temperature detector response, stabilized internally to external temperature change.
Time it takes for the sensor internal stabilization is determined by the thermal mass and conduction resistance of the device.

Installation

Sensor placement in the medium and enclosure considerations.
Methods for minimizing thermal time constant for efficient response.

Calibration

Calibration techniques for different sensor types use known temperature standards.
Ensuring measurement accuracy requires regular calibration.

Protection

Methods to protect the device from damage and maintain functionality.
Including over-temperature protection, environmental considerations, and enclosure.

Range and Accuracy

Characteristics of different sensors regarding their acceptable temperature ranges.
Accuracy measurements as related to full scale deviation (FSD).

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Description

Test your knowledge on temperature measurement and the different temperature scales. This quiz covers concepts like molecular motion, heat transfer mechanisms, and the importance of precise temperature measurement in various applications. Get ready to challenge yourself with these fascinating questions!