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Unformatted text preview: s temperature increases
as Judah Levine, 2170L11 14 The data
Ding! Judah Levine, 2170L11 15 The Theory
Rayleigh dI λ = 8πkT λ 4 dλ Wien Distribution Law: dI λ = kc λ 2 5 e − hc
λkT Judah Levine, 2170L11 16 Comparing Theories Judah Levine, 2170L11 17 The source of the problem
What is relationship between frequency
of radiation and radiated power?
Classical answer: Power proportional to
– No explicit dependence on frequency Amplitude and power are continuous
parameters Judah Levine, 2170L11 18 Quantum principle
Electromagnetic energy transmitted in
discrete packets: “photons”
– Energy of photon= E= hν= hc/λ
– Number of photons decreases when
• hν >> kT
• hc/λ >> kT
• λ << hc/kT Judah Levine, 2170L11 19 Importance of Black Body spectrum
Quantum formulation of
Background radiation in the universe is
a black body spectrum at 2.7 K
Calibration of thermometers in the
Systematic offset of primary standards
“Night vision” optics
Judah Levine, 2170L11 20...
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This note was uploaded on 01/29/2014 for the course PHYSICS 2170 taught by Professor Judahlevine during the Spring '13 term at Colorado.
- Spring '13