- Temperature is a measure of the average kinetic energy of the particles in a substance.
- Heat is the transfer of thermal energy between systems due to a temperature difference.
- There are three primary temperature scales used in thermodynamics: Celsius, Fahrenheit, and Kelvin.
- The Celsius scale (°C) is widely used in most parts of the world and in scientific work.
- In the Celsius scale, the freezing point of water is 0°C and the boiling point is 100°C at standard atmospheric pressure.
- The Fahrenheit scale (°F) is primarily used in the United States for everyday temperature measurements.
- In the Fahrenheit scale, the freezing point of water is 32°F, and the boiling point is 212°F at standard atmospheric pressure.
- The Kelvin scale (K) is the SI unit of temperature and is used in scientific calculations.
- The Kelvin scale is an absolute scale, starting at absolute zero, where molecular motion ceases.
- Absolute zero is 0 K, equivalent to -273.15°C or -459.67°F.
- The relationship between Celsius and Kelvin is: K = °C + 273.15.
- The relationship between Celsius and Fahrenheit is: °F = (°C × 9/5) + 32.
- To convert Fahrenheit to Celsius: °C = (°F − 32) × 5/9.
- To convert Kelvin to Celsius: °C = K − 273.15.
- To convert Kelvin to Fahrenheit: °F = (K − 273.15) × 9/5 + 32.
- The Kelvin scale is used in fields such as physics, astronomy, and engineering where absolute temperature is required.
- Each unit on the Celsius and Kelvin scales represents the same magnitude of temperature difference.
- The Fahrenheit scale has smaller divisions, with one degree Fahrenheit equaling 5/9 of a degree Celsius.
- Temperature scales are essential for scientific, industrial, and everyday applications.
- The Celsius scale is also called the centigrade scale due to its 100-degree interval between freezing and boiling points of water.
- The Kelvin scale does not use the term degrees, and temperature is simply written as K.
- Anders Celsius developed the Celsius scale in 1742, initially inverted, where 0°C was the boiling point and 100°C was the freezing point of water.
- The current Celsius scale was reversed to align with intuitive temperature measurements.
- Daniel Gabriel Fahrenheit developed the Fahrenheit scale in 1724 using mercury thermometers.
- The Rankine scale is another absolute temperature scale, used primarily in thermodynamics, with units similar to Fahrenheit.
- The freezing and boiling points of water on the Rankine scale are 491.67°R and 671.67°R, respectively.
- All temperature scales are interconvertible using mathematical relationships, ensuring universal application.
- Absolute zero has never been physically achieved but is a theoretical limit in thermodynamics.
- In scientific measurements, the Kelvin scale ensures precision, eliminating negative values for thermal energy.
- Temperature scales are used to calibrate instruments like thermometers, thermocouples, and infrared sensors.
- In astronomy, the temperature of stars and cosmic background radiation is measured in Kelvin.
- Everyday weather reports commonly use the Celsius or Fahrenheit scales depending on the region.
- Industrial processes, such as metalworking and food processing, rely on specific temperature measurements for quality control.
- The choice of temperature scale depends on the field of application and regional conventions.
- Climate studies often use the Celsius scale to represent global temperature variations.
- The Kelvin scale simplifies thermodynamic equations by directly correlating temperature with energy.
- Fahrenheit's finer scale is useful for measuring precise changes in daily weather conditions.
- The boiling point of water varies slightly depending on altitude and atmospheric pressure.
- Scientific experiments often use Kelvin to avoid ambiguities related to negative temperatures.
- Knowledge of all three temperature scales is essential for engineers, physicists, chemists, and meteorologists.
- Temperature scales play a crucial role in understanding concepts such as heat transfer, entropy, and thermal expansion.