thermal agitation

Examples of thermal agitation in the following topics:

• Paramagnetism and Diamagnetism

  • In pure paramagnetism, the dipoles do not interact with each other and are randomly oriented in the absence of an external field due to thermal agitation; this results in a zero net magnetic moment.
  • Unlike ferromagnets, paramagnets do not retain any magnetization in the absence of an externally applied magnetic field, because thermal motion randomizes the spin orientations responsible for magnetism.

• Dependence of Resistance on Temperature

  • They become better conductors at higher temperature because increased thermal agitation increases the number of free charges available to carry current.
  • The device is small so it quickly comes into thermal equilibrium with the part of a person it touches.

• Microwaves

  • ., they are a component of electromagnetic radiation generated by thermal agitation.
  • The thermal motion of atoms and molecules in any object at a temperature above absolute zero causes them to emit and absorb radiation.

• Thermal Stresses

  • 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

  • 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.

• A Review of the Zeroth Law

  • 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.

• Thermal Radiation

  • $\displaystyle \text{Another Kirchoff's Law: }S_\nu = B_\nu(T) \text{ for a thermal emitter}$
  • 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

  • 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

• Linear Expansion

  • 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.

• Thermal Bremsstrahlung Emission

  • 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