Grade 9
  1. Mechanics  1.1. Motion  1.1.1. Types of motion  1.1.2. Distance and displacement  1.1.3. Speed and Velocity  1.1.4. Acceleration  1.1.5. Graphical representation of motion  1.1.6. Equations of motion  1.1.7. Uniform and non-uniform motion  1.1.8. Free fall and acceleration due to gravity  1.1.9. Relative speed  1.1.10. Circular motion  1.2. Laws of force and motion  1.2.1. The concept of force  1.2.2. newton's first law of motion  1.2.3. Newton's second law of motion  1.2.4. Newton's third law of motion  1.2.5. Inertia and types of inertia  1.2.6. Motion  1.2.7. Conservation of momentum  1.2.8. Application of Newton's laws in daily life  1.2.9. Types of Forces (Contact and Non-Contact)  1.2.10. Friction and its effects  1.3. Gravitational force  1.3.1. Newton's law of universal gravitation  1.3.2. Importance of Gravitational Force  1.3.3. Acceleration due to gravity  1.3.4. Free fall and weightlessness  1.3.5. Mass and weight  1.3.6. Variation of g with height and depth  1.3.7. Kepler's laws of planetary motion  1.3.8. Satellites and their orbits  1.4. Work, Energy and Power  1.4.1. Concept of work  1.4.2. Positive and negative actions  1.4.3. Work done by constant and variable force  1.4.4. Energy and its forms  1.4.5. Kinetic energy and potential energy  1.4.6. Law of conservation of energy  1.4.8. Commercial unit of energy  1.4.9. Work–energy theorem  1.5. Simple machines  1.5.1. Types of simple machines  1.5.2. Mechanical advantage  1.5.3. Machine efficiency  1.5.4. Levers and their types  1.5.5. Pulleys and Inclined Planes  1.5.6. Gears and their uses
  2. Properties of matter  2.1. States of matter  2.1.1. Solids, liquids and gases  2.1.2. Properties of different states of matter  2.1.3. Change in state of matter  2.1.4. Plasma and Bose–Einstein condensate  2.2. Density and pressure  2.2.1. Concept of density and relative density  2.2.2. Pressure in solids, liquids and gases  2.2.3. Pascal's law and its applications  2.2.4. Atmospheric pressure and its variations  2.2.5. Surface tension and capillarity  2.3. Buoyancy and Archimedes' principle  2.3.1. Buoyant force  2.3.2. Archimedes principle  2.3.3. Applications of Archimedes' Principle  2.3.4. floating and sinking objects  2.3.5. Theory of Flotation and Archimedes' Principle
  3. Heat and Thermodynamics  3.1. Temperature and heat  3.1.1. Concept of heat and temperature  3.1.2. Temperature measurement  3.1.3. Temperature scales  3.2. Heat transfer  3.2.1. Conduction of heat  3.2.2. Convection of heat  3.2.3. heat radiation  3.2.4. Applications of heat transfer  3.2.5. Thermal conductivity  3.3. Thermal expansion  3.3.1. Expansion of solids, liquids and gases  3.3.2. Abnormal expansion of water  3.3.3. Applications of Thermal Expansion  3.4. Specific heat capacity and latent heat  3.4.1. Concept of specific heat capacity  3.4.2. Measurement and applications of specific heat  3.4.3. Latent heat of fusion and vaporization  3.4.4. Heat Engines and Efficiency
  4. Waves and sound  4.1. Waves and their types  4.1.1. Mechanical and electromagnetic waves  4.1.2. Longitudinal and Transverse Waves  4.1.3. Properties of Waves  4.1.4. Wavelength, frequency and speed of the wave  4.1.5. Superimposition of waves  4.2. Sound waves  4.2.1. Nature and transmission of sound  4.2.2. Speed of sound in different mediums  4.2.3. Reflection of sound and echo  4.2.4. Sonar and ultrasound  4.2.5. Resonance and pulsation  4.3. Sound characteristics  4.3.1. Intensity, loudness and quality of sound  4.3.2. Doppler effect in sound
  5. Lighting and Optics  5.1. Reflection of light  5.1.1. Laws of reflection  5.1.2. Reflection from a plane mirror  5.1.3. Reflection from a spherical mirror  5.1.4. Image formation by concave and convex mirrors  5.1.5. Applications of Reflection  5.2. Refraction of light  5.2.1. Laws of refraction  5.2.2. Refractive index  5.2.3. Refraction through a glass slab  5.2.4. Refraction in water and air  5.2.5. Lenses and their types  5.2.6. Image formation by convex and concave lenses  5.2.7. Total internal reflection and its applications  5.3. Dispersion and scattering of light  5.3.1. Spectrum of white light  5.3.2. Prisms and Dispersion  5.3.3. Tyndall effect and blue sky
  6. Electricity and Magnetism  6.1. Electric charge and static electricity  6.1.1. The concept of electric charge  6.1.2. Charging by friction, contact and induction  6.1.3. Electroscope and its working  6.2. Current Electricity  6.2.1. The concept of electric current  6.2.2. Ohm's Law and Resistance  6.2.3. Factors affecting resistance  6.2.4. Series and Parallel Circuits  6.2.5. Heating effect of electric current  6.2.6. Electric power and energy  6.3. Magnetism  6.3.1. Natural and artificial magnets  6.3.2. Properties of magnets  6.3.3. Earth's magnetism  6.3.4. Magnetic field and field lines  6.3.5. Electromagnets and their applications
  7. Modern Physics  7.1. structure of the atom  7.1.1. Atomic Structure and Subatomic Particles  7.1.2. Electrons, Protons, and Neutrons  7.1.3. Rutherford and Bohr model  7.2. Radioactivity  7.2.1. Types of radioactive emissions  7.2.2. Half-life and radioactive decay  7.2.3. Uses and Hazards of Radioactivity
  8. Space science and astronomy  8.1. The universe and its components  8.1.1. Stars and galaxies  8.1.2. Planets and Solar System  8.2. Satellites  8.2.1. Natural and artificial satellites  8.2.2. Use of satellites

Grade 9 → Heat and Thermodynamics → Temperature and heat ↓


Temperature measurement


In our daily lives, we constantly encounter temperature. Whether we are checking how hot it is outside or adjusting the thermostat in our homes, temperature plays an important role. Understanding how temperature is measured is important and is a fundamental aspect of physics, especially when learning about heat and thermodynamics.

What is the temperature?

Temperature is a measure of how hot or cold something is. It refers to the amount of thermal energy present within an object. When we talk about the temperature of an object, we are essentially describing the average kinetic energy of its particles.

Physics of temperature

All matter is made up of particles that are in constant motion. The faster these particles move, the more kinetic energy they have and the hotter the object is. Conversely, slower moving particles represent a colder object. Thus, temperature measures the average kinetic energy of the particles in a substance.

Temperature ∝ Average Kinetic Energy of Particles

Temperature measurement scale

There are several scales used to measure temperature. The most common scales are Celsius, Fahrenheit, and Kelvin.

Celsius scale

The Celsius scale, also known as the centigrade scale, is widely used around the world, especially for everyday measurements. It defines 0°C as the freezing point of water and 100°C as the boiling point of water at standard atmospheric pressure.

°C = (°F - 32) × 5/9

Fahrenheit scale

In countries such as the United States, the Fahrenheit scale is commonly used. In this scale, water freezes at 32°F and boils at 212°F. The Fahrenheit scale provides a larger degree of division in thermometers, which can be particularly useful in certain scientific scenarios.

°F = (°C × 9/5) + 32

Kelvin scale

The Kelvin scale is used primarily in scientific contexts, as it starts at the absolute zero point, where there is no molecular motion. On this scale, water freezes at about 273.15 K and boils at 373.15 K.

K = °C + 273.15

How is temperature measured?

Temperature can be measured using a variety of instruments known as thermometers. These instruments vary depending on what they are measuring and what temperature range they are able to measure.

Mercury thermometer in glass

One of the most traditional instruments for measuring temperature is the mercury thermometer in glass. The mercury in it expands and contracts as the temperature changes, giving a visual reading on a scale imprinted on the glass.

Digital thermometer

Digital thermometers have become more common due to their ease of use, quick readings, and accuracy. They use electronic sensors to determine the temperature and then display the reading digitally.

Applications of temperature measurement

Temperature measurement is important in a variety of areas:

  • In the medical field, it helps in diagnosing and monitoring fever and other health conditions.
  • In cooking, it ensures that the food is delicious and safe to eat.
  • In industrial processes, accurate temperature measurement can ensure product quality and safety.

Practical example

Let's consider some practical examples of temperature measurement:

Example 1: Weather forecast

The weather forecasts you see in the news rely heavily on temperature measurements. Meteorologists collect data from thermometers placed in different locations to forecast the day's weather. If your city records a temperature of 25°C one morning, it means that the air particles have a certain average kinetic energy.

Example 2: Cooking food

When cooking, especially baking, precise temperatures ensure that food is cooked evenly. For example, an oven set to 200°C indicates that the air inside the oven has a consistent level of thermal energy to cook food properly.

Example 3: Human body temperature

The normal body temperature is around 37°C. If it is higher than this, it may be a sign of fever, which indicates that particles in the body have more kinetic energy than normal due to the immune response.

Understanding temperature conversions

There are many occasions when you need to convert temperature between different scales. Here are some conversion formulas:

Celsius to Fahrenheit

°F = (°C × 9/5) + 32

From Fahrenheit to Celsius

°C = (°F - 32) × 5/9

Celsius to Kelvin

K = °C + 273.15

Kelvin to Celsius

°C = K - 273.15

Conclusion

Temperature is a fundamental aspect of our everyday lives and understanding how it is measured is important in many scientific disciplines. From meteorological predictions to the safe preparation of food, temperature measurement has many applications. Different temperature scales such as Celsius, Fahrenheit and Kelvin provide flexibility and accuracy for different contexts, and modern advancements have made temperature measurement easier and more reliable than ever.

Encourage exploration

By understanding and exploring more about how temperature works and why it is important, you can better understand the world around you as well as the scientific principles that govern it.


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Temperature measurement

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