Physics

Thermal Properties of Matter

January 18, 2024
admin

Terms and Definitions

  • Thermal Expansion:
  • The tendency of a substance to change its shape, area, and volume in response to a change in temperature.
  • Specific Heat Capacity:
  • The amount of heat energy required to raise the temperature of a unit mass of a substance by one degree Celsius.
  • Thermal Conductivity:
  • The ability of a material to conduct heat. It is a measure of how fast heat can be transferred through a substance.
  • Conduction:
  • The process of heat transfer through a material by direct contact of particles within the material, without any overall movement of the material itself.
  • Convection:
  • The transfer of heat through the movement of fluids (liquids or gases) caused by differences in temperature.
  • Radiation:
  • The transfer of heat through electromagnetic waves, such as infrared radiation, without the need for a medium (solid, liquid, or gas) to carry the heat.
  • Heat Capacity:
  • The amount of heat energy required to change the temperature of an entire object by one degree Celsius.
  • Latent Heat:
  • The heat energy absorbed or released during a change of phase (e.g., melting, freezing, vaporization, condensation) without a change in temperature.
  • Phase Transition:
  • The process of changing from one state of matter to another, such as from solid to liquid or liquid to gas.
  • Melting Point:
  • The temperature at which a substance changes from a solid to a liquid state.
  • Boiling Point:
  • The temperature at which a substance changes from a liquid to a gaseous state.
  • Evaporation:
  • The process by which a substance changes from a liquid to a gas at temperatures below its boiling point, typically at the surface of the liquid.
  • Heat Transfer:
  • The movement of heat energy from one location to another, either within the same substance or between different substances.
  • Thermodynamics:
  • The branch of physics that deals with the relationships between heat and other forms of energy, and the principles governing the conversion of one form of energy into another.

Important Formulae

1. Thermal Expansion:
– Formula: \Delta L = \alpha \cdot L_0 \cdot \Delta T
– Symbols:
– \Delta L: Change in length
– \alpha: Coefficient of linear expansion
– L_0: Initial length
– \Delta T: Change in temperature
– SI Unit: meter (m)

2. Specific Heat Capacity:
– Formula: Q = mc\Delta T
– Symbols:
– Q: Heat energy
– m: Mass
– c: Specific heat capacity
– \Delta T: Change in temperature
– SI Unit: Joule (J)

3. Latent Heat:
– Formula (for phase change): Q = mL
– Symbols:
– Q: Heat energy
– m: Mass
– L: Latent heat
– SI Unit: Joule (J)

4. Boyle’s Law (for gases):
– Formula: PV = \text{constant}
– Symbols:
– P: Pressure
– V: Volume
– SI Units: Pascal (Pa), cubic meter (m^3)

5. Charles’s Law (for gases):
– Formula: \frac{V}{T} = \text{constant}
– Symbols:
– V: Volume
– T: Temperature (in Kelvin)
– SI Units: Cubic meter (m^3), Kelvin (K)

6. Ideal Gas Law:
– Formula: PV = nRT
– Symbols:
– P: Pressure
– V: Volume
– n: Number of moles
– R: Gas constant (8.314 J/(mol·K))
– T: Temperature (in Kelvin)
– SI Units: Pascal (Pa), cubic meter (m^3), mole (mol), Joule (J), Kelvin (K)

7. Stefan-Boltzmann Law:
– Formula: P = \varepsilon \sigma AT^4
– Symbols:
– P: Power radiated
– \varepsilon: Emissivity of the material
– \sigma: Stefan-Boltzmann constant (5.67 \times 10^{-8} \, \text{W/(m}^2 \cdot \text{K}^4))
– A: Surface area
– T: Temperature (in Kelvin)
– SI Units: Watt (W), square meter (m^2), Kelvin (K)

8. Newton’s Law of Cooling:
– Formula: \Delta T = -k \Delta t
– Symbols:
– \Delta T: Temperature difference
– k: Cooling constant
– \Delta t: Time interval
– SI Unit: Kelvin (K)