Curie temperature
(noun)
The temperature above which a material will lose its magnetism.
Examples of Curie temperature in the following topics:
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Ferromagnets and Electromagnets
- Increased thermal motion at higher temperature can disrupt and randomize the orientation and the size of the domains.
- There is a well-defined temperature for ferromagnetic materials called the Curie temperature, above which they cannot be magnetized.
- The Curie temperature for iron is well above room temperature at 1043 K (770ºC).
- Several elements and alloys have Curie temperatures much lower than room temperature, and are ferromagnetic only below those temperatures.
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Discovery of Radioactivity
- In addition, radiation does not vary with temperature, pressure, or ionization state of the uranium atom.
- In 1898, Marie Curie began her doctoral study of Becquerel's rays.
- The Curies' radium salt glowed visibly from the radiation.
- Shortly after Marie completed her PhD, both Curies and Becquerel shared the 1903 Nobel Prize in Physics for their work on radioactivity.
- Awarded the 1911 Nobel Prize in Chemistry for her discovery of two new elements, Curie remains the only person to win Nobel Prizes in both physics and chemistry.
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Dependence of Resistance on Temperature
- Resistivity and resistance depend on temperature with the dependence being linear for small temperature changes and nonlinear for large.
- The resistivity of all materials depends on temperature.
- The temperature coefficient is typically +3×10−3 K−1 to +6×10−3 K−1 for metals near room temperature.
- Above that critical temperature, its resistance makes a sudden jump and then increases nearly linearly with temperature.
- Compare temperature dependence of resistivity and resistance for large and small temperature changes
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Absolute Temperature
- Absolute temperature is the most commoly used thermodyanmic temperature unit and is the standard unit of temperature.
- Thermodynamic temperature is the absolute measure of temperature.
- Thermodynamic temperature is an "absolute" scale because it is the measure of the fundamental property underlying temperature: its null or zero point ("absolute zero") is the temperature at which the particle constituents of matter have minimal motion and cannot become any colder.
- By using the absolute temperature scale (Kelvin system), which is the most commonly used thermodynamic temperature, we have shown that the average translational kinetic energy (KE) of a particle in a gas has a simple relationship to the temperature:
- The kelvin (or "absolute temperature") is the standard thermodyanmic temperature unit.
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Blackbody Temperatures
- A blackbody is of course characterized by a single temperature, $T$.
- There are three characteristic temperatures in common usage: brightness temperature, effective temperature and the colour temperature.
- The brightness temperature is determined by equating the brightness or intensity of an astrophysical source to the intensity of a blackbody and solving for the temperature of the corresponding blackbody.
- In what regime does the linear relationship between the brightness temperature and the intensity begin to fail?
- Finally the effective temperature is the temperature of a blackbody that emits the same flux at its surface as the source, i.e.
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Rate of Radioactive Decay
- Another unit of radioactivity is the curie, Ci, which was originally defined as the amount of radium emanation (radon-222) in equilibrium with one gram of pure radium, isotope Ra-226.
- At present, it is equal, by definition, to the activity of any radionuclide decaying with a disintegration rate of 3.7 × 1010 Bq, so that 1 curie (Ci) = 3.7 × 1010 Bq.
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Blackbody Radiation
- A blackbody is of course characterized by a single temperature, $T$.
- There are three characteristic temperatures in common usage: brightness temperature, effective temperature and the colour temperature.
- The brightness temperature has several nice properties.
- The colour temperature is defined by looking at the peak of the emission from the source and using Wien's displacement law to define a corresponding temperature.
- Finally the effective temperature is the temperature of a blackbody that emits the same flux at its surface as the source, i.e.
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Absolute Zero
- Absolute zero is the coldest possible temperature; formally, it is the temperature at which entropy reaches its minimum value.
- Absolute zerois the coldest possible temperature.
- Formally, it is the temperature at which entropy reaches its minimum value.
- Therefore, it is a natural choice as the null point for a temperature unit system.
- A brief introduction to temperature and temperature scales for students studying thermal physics or thermodynamics.
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Thermodynamics
- A blackbody is of course characterized by a single temperature, $T$.
- There are three characteristic temperatures in common usage: brightness temperature, effective temperature and the colour temperature.
- The brightness temperature is determined by equating the brightness or intensity of an astrophysical source to the intensity of a blackbody and solving for the temperature of the corresponding blackbody.
- In what regime does the linear relationship between the brightness temperature and the intensity begin to fail?
- Finally the effective temperature is the temperature of a blackbody that emits the same flux at its surface as the source, i.e.
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Solid Solubility and Temperature
- Solubility often depends on temperature; the solubility of many substances increases with increasing temperature.
- The solubility of a given solute in a given solvent typically depends on temperature.
- Many salts show a large increase in solubility with temperature.
- Some solutes exhibit solubility that is fairly independent of temperature.
- A few, such as cerium(III) sulfate, become less soluble in water as temperature increases.