Flashcards
Classical Physics and Wave-Particle Duality
Cards in this deck (14)
- 1what is a black bodyan object capable of absorbing and emitting all wavelengths of radiation uniformly
- 2what is an example of black body approximatea hollow container with a pinhole maintained at constant temperature.
radiation emitted and absorbed through the pinhole can be detected. - 3what is energy densitythe amount of energy for a given wavelength ρ(λ,T)
- 4explain what you would see on an energy density vs wavelength plotx axis = wavelength
y axis = energy density
energy density = 0 for small and large wavelengths
as temperature increases the max of energy density increases - 5what does classical physics say about black body radiationto treat the electromagentic field in the container as a collection of oscillators with all possible frequencies (no constraint on energy)
- 6how does energy density given for a black body in classical terms compare to experimental valuesgood agreement at large wavelengths
at low wavelengths, energy density diverges to infinity in classical terms when it should approach zero experimentally - 7what is the ultraviolet catastrophewhen black body radiation approaches infinity at low wavelengths instead of approaching zero, it is the reason classical physics cannot account for black body radiation
- 8how was the expression for energy density of a black body solvedwith quantisation of energy
- the concept that electromagnetic field has discrete energies
E=nhv (where n=integers) - 9what is the correspondence principlequantum mechanics reproduces classical physics in the limit of large quantum numbers
- 10what does the heat capacity representthe amount of energy required to change the temperature of a body
- 11what does classical phsyics predict for heat capacitythat heat capacity is independent of temperature as U=3RT
C_v=(∂U/∂T)_v=3R
(plotting C_v vs T would get the constant 3R) - 12what actually happens to heat capacity at low temperatures and howdrops off to zero from 3R as temp is reduced
- 13why does heat capacity when quantised drop off at low temperatures?atoms in the material have certain allowed discrete values (oscillate at a single frequency). this means that at low temperatures/when energy thats put into the system is reduced there s not enough energy to make the atoms vibrate therefore heat capacity drops off to 0
- 14what is wave-particle dualitythe concept that every particle can show properties of both particles and waves and that classical concepts cannot fully describe quantum-scale objects
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- Chemistry (ess) Flashcards on Classical Physics and Wave-Particle Duality, created by Casey Champion on 18/05/2023.
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- Casey Champion · May 2023
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- May 18, 2023
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