Examples of thermal conductivity in the following topics:
-
- (The matter is stationary on a macroscopic scale—we know there is thermal motion of the atoms and molecules at any temperature above absolute zero. ) Heat transferred from an electric stove to the bottom of a pot is an example of conduction.
- Some materials conduct thermal energy faster than others.
- Conduction is the most significant means of heat transfer within a solid or between solid objects in thermal contact.
- Lastly, the heat transfer rate depends on the material properties described by the coefficient of thermal conductivity.
- where Q/t is the rate of heat transfer in Joules per second (Watts), k is the thermal conductivity of the material, A and d are its surface area and thickness, and (T2−T1) is the temperature difference across the slab.
-
- This range of wavelengths corresponds to a frequency range of approximately 300 GHz to 400 THz, and includes most of the thermal radiation emitted by objects near room temperature.
- Unlike heat transmitted by thermal conduction or thermal convection, radiation can propagate through a vacuum.
- This is a property of a surface which describes how its thermal emissions deviate from the ideal of a black body.
- The range of wavelengths most relevant to thermally emitting objects on earth is often called the thermal infrared.
- Many astronomical objects emit detectable amounts of IR radiation at non-thermal wavelengths.
-
- Solids also undergo thermal expansion.
- What are the basic properties of thermal expansion?
- What is the underlying cause of thermal expansion?
- Thermal stress is created by thermal expansion or contraction.
- Another example of thermal stress is found in the mouth.
-
- The Zeroth Law of Thermodynamics states that systems in thermal equilibrium are at the same temperature.
- Systems are in thermal equilibrium if they do not transfer heat, even though they are in a position to do so, based on other factors.
- If A and C are in thermal equilibrium, and A and B are in thermal equilibrium, then B and C are in thermal equilibrium.
- Temperature is the quantity that is always the same for all systems in thermal equilibrium with one another.
- The double arrow represents thermal equilibrium between systems.
-
- The Zeroth Law of Thermodynamics states: If two systems, A and B, are in thermal equilibrium with each other, and B is in thermal equilibrium with a third system, C, then A is also in thermal equilibrium with C.
- Two systems are in thermal equilibrium if they could transfer heat between each other, but don't.
- Indeed, experiments have shown that if two systems, A and B, are in thermal equilibrium with each other, and B is in thermal equilibrium with a third system C, then A is also in thermal equilibrium with C.
- The answer lies in the fact that any two systems placed in thermal contact (meaning heat transfer can occur between them) will reach the same temperature.
- The objects are then in thermal equilibrium, and no further changes will occur.
-
- $\displaystyle \text{Another Kirchoff's Law: }S_\nu = B_\nu(T) \text{ for a thermal emitter}$
- Because $I_\nu=B_\nu(T)$ outside of the thermal emitting material and $S_\nu=B_\nu(T)$ within the material, we find that $I_\nu=B_\nu(T)$ through out the enclosure.
- If we remove the thermal emitter from the blackbody enclosure we can see the difference between thermal radiation and blackbody radiation.
- A thermal emitter has $S_\nu = B_\nu(T)$,$B_\nu(T)$ so the radiation field approaches $B_\nu(T)$ (blackbody radiation) only at large optical depth.
-
- Thermal pollution is the degradation of water quality by any process that changes ambient water temperature.
- Thermal pollution is the degradation of water quality by any process that changes ambient water temperature.
- Some fish species will avoid stream segments or coastal areas adjacent to a thermal discharge.
- Some may assume that by cooling the heated water, we can possibly fix the issue of thermal pollution.
- Identify factors that lead to thermal pollution and its ecological effects
-
- Conduction is heat transfer through stationary matter by physical contact. ( The matter is stationary on a macroscopic scale—we know there is thermal motion of the atoms and molecules at any temperature above absolute zero. ) Heat transferred between the electric burner of a stove and the bottom of a pan is transferred by conduction.
- A less obvious example is thermal radiation from the human body.
-
- Thermal expansion is the tendency of matter to change in volume in response to a change in temperature.
- Thermal expansion is the tendency of matter to change in volume in response to a change in temperature.
- This kind of excitation is called thermal motion.
- The degree of expansion divided by the change in temperature is called the material's coefficient of thermal expansion; it generally varies with temperature.
- Thermal expansion of long continuous sections of rail tracks is the driving force for rail buckling.
-
- The most important case astrophysically is thermal bremsstrahlung where the electrons have a thermal distribution so the probablility of a particle having a particular velocity is
- ${\bar g}_{ff}$ is the thermally averaged Gaunt factor.
- Thermal bremsstrahlung spectra for two temperatures that differ by a factor of ten