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# DC Pandey Thermometry, Thermal Expansion & Kinetic Theory of Gases Solutions

DC Pandey Waves and Thermodynamics Solutions for Chapter 17 ‘Thermometry, Thermal Expansion and Kinetic Theory of Gases’ will aid you in understanding the basics of thermodynamics for Class 11 and Class 12. The concepts in this chapter of DC Pandey Solutions include Thermometers and the Celsius Temperature Scale, Constant Volume Gas Thermometer, the Absolute Temperature Scale, Quantity of Heat, and Thermal Expansion. In this chapter, you will learn about the concepts of an Ideal Gas, Gas Laws, Ideal Gas Equation and Internal Energy of an Ideal Gas, Degree of Freedom, Law of Equipartition of Energy, Molar Heat Capacity, Kinetic Theory of Gases.

DC Pandey Thermometry, Thermal Expansion and Kinetic Theory of Gases Chapter includes 121 practice questions divided into 3 Introductory exercises with exercises for JEE Main and JEE advanced. You will get to solve questions of a wide variety of both subjective and objective types. All the patterns of questions asked in the competitive exams are covered in detail in this chapter including the assertion-reasoning, multiple-choice questions, match the columns, fill in the blanks, and long-answer type numerical questions. You will get to solve problems of increased difficulty level in the DC Pandey Waves and Thermodynamics Chapter 17.

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## Important Topics for DC Pandey Waves and Thermodynamics Solutions Chapter 17: Thermometry, Thermal Expansion and Kinetic Theory of Gases

Thermometers and Celsius Temperature Scale

Thermometers are based on the concept that there is a change in the physical properties of a given system with respect to the change in temperatures such as volume, length, pressure, or electric resistance.

In a liquid thermometer, the volume of alcohol or mercury expands to rise inside the curated scale. A degree Celsius thermometer scale comprises the lowest mark as 0 degree C and the highest mark of 100 degree C.

Constant Volume Gas Thermometer and the Absolute Temperature Scale

The physical property that is employed in a constant volume gas thermometer is the pressure variation in a gas at constant volume. At a temperature of -273.15 degree C, the pressure of all gases is zero. Therefore, this temperature is used as the zero-point in the absolute temperature scale.

The SI unit of temperature is Kelvin. It was adopted in 1954. 1 Kelvin can be defined as the 1/273.16 part of the difference between absolute zero and the triple point of water. Where ΔTc is the temperature on the Celsius scale

T is the temperature in the Kelvin scale

ΔTf is the temperature in the Fahrenheit scale.

Quantity of Heat

The flow of heat is generally from a body at a higher temperature to a body at a lower temperature. Such a flow of energy is termed as heat flow or heat transfer. The unit of heat is a calorie. 1 calorie can be defined as the amount of heat used to raise the temperature of 1 gram of water from 14.5 degree C to 15.5 degree C.

Thermal Expansion

As the temperature in a solid increase, the atoms begin to move with a greater amplitude than the equilibrium oscillation of 10-11 m. Because of larger oscillations, solids tend to expand as the temperatures increase

1. Linear Expansion: Δl=lαΔT, where Δl changes in length, l is the original length, ΔT is the change in temperature and α is the coefficient of linear expansion.
2. Volume Expansion: ΔV=VγΔT, where ΔV is the changes in volume, V is the original Value and ΔT is the change in temperature and α is the coefficient of linear expansion.

Concept of an Ideal Gas

An ideal gas exerts no pressure or attraction between its molecules and has no volume, and thus are point masses. A real gas exhibits the behaviour of an ideal gas at low pressure and high temperature.

Gas Laws

• Boyle’s Law: For a given mass of a gas, in an isothermal process • Charles’ Law: For an isobaric process, • Pressure Law: For an isochoric process, • Avogadro’s Law states that at a constant temperature and pressure, an equal volume of gases contains an equal number of molecules.

Ideal Gas Equation and

At constant temperature, pressure, and volume

PV=nRT

n is the number of moles of the gas and R is the universal constant.

Degree of Freedom

It is denoted by f and it represents the number of ways a given thermodynamic system can have energy.

Internal Energy of an Ideal Gas

U= KT+KR

Where U is the internal energy, KT is translational Kinetic Energy and KR is the rotational Kinetic Energy.

Molar Heat Capacity and Kinetic Theory of Gases

Molar Heat Capacity is the amount of heat required to raise the temperature of 1 mole of a system by 1K. In the Kinetic theory of gases, you will study the mechanics of a large number of particles in a monatomic gas.

### Exercise Discussion for DC Pandey Waves and Thermodynamics Solutions Chapter 17: Thermometry, Thermal Expansion and Kinetic Theory of Gases

Introductory Exercises:

• Exercise 17.1 is based on the basic concepts of the absolute temperature scale and Celsius Temperature scale.
• The questions in 17.2 employ the concepts of thermal expansion and quantity of heat besides the gas laws.
• In exercise 17.3, you will get to solve problems related to the kinetic theory of gases, and molar heat capacity.

Exercise for JEE Main:

43 subjective questions covering numerical problems on topics of the absolute temperature scale, Gas Laws, Degree of Freedom, Molar Heat Capacity, and Kinetic Theory of Gases have been given in this exercise. In this exercise, these topics are also included in a multiple-choice question format.