Grade 10
  1. Mechanics  1.1. Dynamics  1.1.1. Motion in one dimension  1.1.2. Motion in two dimensions  1.1.3. Displacement and Distance  1.1.4. Speed and Velocity  1.1.5. Acceleration  1.1.6. Graphical representation of motion  1.1.7. Equations of motion  1.1.8. Free fall and acceleration due to gravity  1.1.9. Projectile motion  1.1.10. Relative speed  1.2. Dynamics  1.2.1. Newton's Laws of Motion  1.2.2. Inertia and mass  1.2.3. Force and its types  1.2.4. action and reaction force  1.2.5. Friction and its effects  1.2.6. Coefficient of friction  1.2.7. Circular motion  1.2.8. Centripetal force and centripetal acceleration  1.2.9. Momentum and Impulse  1.2.10. Conservation of momentum  1.2.11. Newton's third law and applications  1.3. Work, Energy and Power  1.3.1. Work done by the force  1.3.2. Work–energy theorem  1.3.3. Kinetic energy  1.3.4. Potential energy  1.3.5. Mechanical energy  1.3.6. Energy Conservation  1.3.7. Power and efficiency  1.3.8. Renewable and non-renewable energy sources  1.4. Gravitational force  1.4.1. Newton's law of universal gravitation  1.4.2. Gravitational field and field strength  1.4.3. Acceleration due to gravity on different planets  1.4.4. Kepler's laws of planetary motion  1.4.5. Orbits and satellites  1.4.6. Weight and apparent weight  1.4.7. Gravitational potential energy
  2. Properties of matter  2.1. States of matter  2.1.1. Solid, liquid and gas  2.1.2. Molecular structure of matter  2.1.3. Intermolecular forces  2.1.4. Plasma and Bose–Einstein condensate  2.2. Pressure  2.2.1. Definition of Pressure  2.2.2. Pressure in liquids  2.2.3. Atmospheric pressure  2.2.4. Pascal's principle  2.2.5. Archimedes' Principle and Buoyancy  2.2.6. Surface tension and capillarity  2.3. Elasticity  2.3.1. Hooke's law  2.3.2. Stress and strain  2.3.3. Elastic Limit and Modulus of Elasticity  2.3.4. Applications of Elasticity
  3. Thermal physics  3.1. heat and temperature  3.1.1. Difference Between Heat and Temperature  3.1.2. Temperature scale  3.1.3. Thermal expansion  3.1.4. Thermal equilibrium  3.2. Heat transfer  3.2.1. Conductivity  3.2.2. Convection  3.2.3. Radiation  3.2.4. Insulation and its applications  3.3. Thermal properties of matter  3.3.1. Specific heat capacity  3.3.2. Latent heat and phase change  3.3.3. Boiling and Melting Point  3.3.4. Heat engines and refrigeration  3.4. Laws of Thermodynamics  3.4.1. Zeroth law of thermodynamics  3.4.2. First law of thermodynamics  3.4.3. Second law of thermodynamics  3.4.4. Carnot cycle
  4. Waves and optics  4.1. Nature and properties of waves  4.1.1. Types of waves in nature and properties of waves  4.1.2. Transverse and longitudinal waves  4.1.3. Wave parameters  4.1.4. Reflection and refraction of waves  4.1.5. Superposition and Interference  4.1.6. Standing Waves and Resonance  4.1.7. Doppler effect  4.2. Sound waves  4.2.1. Characteristics of sound waves  4.2.2. Speed of sound in different mediums  4.2.3. Applications of sound waves  4.2.4. Ultrasound and its uses  4.3. Light Waves and Optics  4.3.1. Nature of light  4.3.2. Reflection of light  4.3.3. Laws of reflection  4.3.4. Mirrors and Image Formation  4.3.5. Refraction of light  4.3.6. Snell's Law  4.3.7. Lenses and Image Formation  4.3.8. Total internal reflection and critical angle  4.3.9. Optical fibre  4.4. Optical Instruments  4.4.1. Microscope  4.4.2. Telescope  4.4.3. Human eye and vision defects  4.4.4. Camera and its working principle
  5. Electricity and Magnetism  5.1. Electrostatics  5.1.1. Electric charge and its properties  5.1.2. Conductors and Insulators  5.1.3. Coulomb's law  5.1.4. Electric field and field lines  5.1.5. Electric potential and potential difference  5.1.6. Capacitors and Capacitance  5.2. Current Electricity  5.2.1. Electric current and its measurement  5.2.2. Ohm's law  5.2.3. Resistance and resistivity  5.2.4. Series and Parallel Circuits  5.2.5. Electric power and energy  5.2.6. Kirchhoff's Laws  5.3. Magnetism and Electromagnetism  5.3.1. Magnetic field and field lines  5.3.2. Magnetic effects of electric current  5.3.3. Electromagnetic induction  5.3.4. Faraday's laws of electromagnetic induction  5.3.5. Transformers and Applications  5.3.6. AC and DC current
  6. Modern Physics  6.1. Nuclear physics  6.1.1. Structure of the atom  6.1.2. Bohr's atomic model  6.1.3. Electron Energy Levels  6.1.4. X-rays and applications  6.2. Radioactivity  6.2.1. Types of radiation  6.2.2. Half-life and radioactive decay  6.2.3. Nuclear reactions and applications  6.2.4. Fission and Fusion  6.3. Quantum physics  6.3.1. Wave–particle duality  6.3.2. Photoelectric effect  6.3.3. Energy quantization  6.3.4. Heisenberg's uncertainty principle
  7. Electronics and Communication  7.1. Semiconductors  7.1.1. Conductors, Insulators and Semiconductors  7.1.2. Diodes and their applications  7.1.3. Transistors and Logic Gates  7.1.4. LEDs and photodiodes  7.2. Communication Systems  7.2.1. Basics of communication  7.2.2. Analog and digital signals  7.2.3. Wireless and optical fibre communication  7.2.4. Radio Waves and Modulation

Grade 10 ↓


Thermal physics


Thermal physics is a branch of physics that deals with the study of heat and temperature and their relationship to energy and work. Heat is a form of energy transfer between particles in a substance (or system) through kinetic energy. In this section, we will explore the main concepts of thermal physics by examining the behavior of particles, understanding heat transfer principles, and more.

Temperature and heat

Temperature measures how hot or cold an object is. It is an average measure of the kinetic energy of the particles in an object. When we measure temperature, we understand that higher temperatures mean the particles are moving faster. The most common units we use to measure temperature are Celsius (°C), Fahrenheit (°F), and Kelvin (K).

Heat, on the other hand, is energy that is transferred from one body to another due to a difference in temperature. When heat is added to a substance, it results in an increase in the energy of motion or kinetic energy of its particles.

Visual example of temperature

ColdHot

In the diagram above, the left bar represents a colder object, where the particles are moving slower. The right bar represents a hotter object, where the particles are moving faster.

Thermal equilibrium

Two objects are in thermal equilibrium if they are at the same temperature and no heat flows between them. This concept is governed by the zeroth law of thermodynamics, which states that if two bodies are in thermal equilibrium with a third body, they are also in thermal equilibrium with each other.

Example of thermal equilibrium

When you put a cube of ice in a cup of water, over time the ice melts, and all the water becomes the same temperature.

Heat transfer methods

Heat can transfer from one body or system to another in three primary ways: conduction, convection, and radiation.

Conductivity

Conduction is the transfer of heat through a substance, without the substance moving. It usually occurs in solids, where the particles are packed very closely together. As the particles heat up, they vibrate more vigorously, transferring energy to neighboring particles.

Example of conduction

Imagine a metal rod placed over a fire. Over time, the end of the rod that is not in the fire becomes hotter due to conduction.

Convection

Convection is the transfer of heat by the movement of a fluid (liquid or gas). When particles in a fluid heat up, they move faster and spread out, causing the fluid to become less dense and rise. Cooler fluid then takes its place, creating a circulation pattern.

Example of convection

Boiling water in a pot on the stove is an example of convection. As the water at the bottom of the pot heats up, it rises, and cooler water sinks to the bottom to be heated.

Radiation

Radiation is the transfer of heat in the form of electromagnetic waves. It does not require any medium, so heat can be transferred through a vacuum. Heat coming from the sun reaches the earth through radiation.

Example of radiation

Feeling the warmth of the sun on your face is an example of radiation.

Specific heat capacity

Specific heat capacity is the amount of heat energy required to raise the temperature of a unit mass of a substance by one degree Celsius (or one Kelvin). Different substances have different specific heat capacities.

Q = mcΔT
  • Q is heat energy (in joules)
  • m is the mass (in kilograms)
  • c is the specific heat capacity (in J/kg°C or J/kgK)
  • ΔT is the change in temperature (in °C or K)

Example calculation

If it takes 4,200 joules of energy to heat 1 kilogram of water from 20°C to 21°C, then the specific heat capacity of water is 4,200 J/kg°C.

Latent heat

Latent heat refers to the heat required to change the phase of a substance (such as from solid to liquid or liquid to gas) without changing its temperature. There are two types: latent heat of fusion and latent heat of vaporization.

Latent heat of fusion

It is the heat required to change a solid into a liquid at its melting point.

Latent heat of vaporization

This is the heat required to change a liquid into a gas at its boiling point.

Q = mL
  • Q is heat energy (in joules)
  • m is the mass (in kilograms)
  • L is latent heat (in joules/kg)

Temperature-volume relation of gases

In thermal physics, gases are often analyzed to understand the relationship between temperature, pressure, and volume. This is important in understanding thermodynamics. The behavior of an ideal gas can be described by Boyle's law, Charles's law, and Gay-Lussac's law, which combine into the ideal gas law:

PV = nRT
  • P is the pressure of the gas (in Pa)
  • V is the volume of the gas (in m³)
  • n is the amount of gas (in moles)
  • R is the universal gas constant (8.314 J/mol-K)
  • T is the temperature (in Kelvin)

Laws of Thermodynamics

First law of thermodynamics

The first law of thermodynamics is a form of the law of conservation of energy. It states that energy cannot be created or destroyed in an isolated system. The change in the internal energy of a system is equal to the heat added to the system minus the work done by the system on its surroundings.

ΔU = Q - W

where ΔU is the change in internal energy, Q is the heat added to the system, and W is the work done by the system.

Second law of thermodynamics

The second law of thermodynamics states that the entropy of any isolated system always increases. Entropy is a measure of the disorder or irregularity in a system. In simple terms, energy conversions are never 100% efficient, and some energy is always lost as heat.

Third law of thermodynamics

The third law of thermodynamics states that the entropy of an ideal crystal at absolute zero is exactly zero. Absolute zero is the lowest temperature where there is no movement of particles and hence no disorder.

Practical applications of thermal physics

Thermal physics is not only theoretical, but it has many practical applications in real life. From everyday experiences to special industrial processes, thermal physics plays a vital role.

Household examples

  • Refrigerator: Use the principle of convection and cooling gases to extract heat from inside and dissipate it outside.
  • Thermos Flask: Reduce or stop heat transfer to keep hot liquids hotter and cold liquids colder for longer periods of time by minimizing conduction, convection, and radiation.

Environmental and industrial examples

  • Power Plants: Most power plants work on the principle of converting heat energy into mechanical energy and then into electrical energy.
  • Climatology: Understanding heat transfer is important in climate models that study the Earth's atmosphere and oceans.

Thermal physics provides a foundation for our understanding of how systems interact through energy transfer, making it an essential part of physics education. By understanding concepts such as temperature, heat, and the laws of thermodynamics, we can better understand the workings of both natural phenomena and technological advancements in our world.


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Thermal physics

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