O Phyical chomitayI Chapter I Introduction of Quantum Meelanics Blackbody is a substance that would absorb all frequencies of radiation falling on it, it would reflect no radiation and appear black Maximum of p 九T= constant Detecte radiatio Pinhole Container at a Increasing temperature temporature Wavelength,入 20218/21 Chemistry Departme nt of Fudan University
Physical ChemistryI Chapter I Introduction of Quantum Mechanics 2021/8/21 Chemistry Department of Fudan University 11 Blackbody is a substance that would absorb all frequencies of radiation falling on it ; it would reflect no radiation and appear black. T = constant m
O Phyical chomitayI Chapter I Introduction of Quantum Meelanics 1. The radiating atoms or molecules of the blackbody can emit and absorb electromagnetic energy as coming in small packets. The packets of energy are called quanta and are only in multiples of the minimum energy ,Eo[2 Rayleigh- 2. The minimum energy o=hv Jeans law Planck distribution M. Planck 0.5 10 1.52 20218/21 Chemistry Departme nt of Fudan University
Physical ChemistryI Chapter I Introduction of Quantum Mechanics 2021/8/21 Chemistry Department of Fudan University 12 1. The radiating atoms or molecules of the blackbody can emit and absorb electromagnetic energy as coming in small packets. The packets of energy are called quanta and are only in multiples of the minimum energy . 2. The minimum energy . M.Planck 0 0 = h
O Phyical chomitayI Chapter I Introduction of Quantum Meelanics ∑6nep(-6n/7 8丌 E(v, T) 8 exp(-En/kT) C vT)=元E(v,T) n=1 8丌 hv E(v,)= planck Equatian C'exphv/kr-1 gher frequency Lower Frequency E(V, T)=oIV E(v, T)=IV h hv/kt h=6.63×10-34J Raleigh- jeans Equ E(v. T 20218/21 Chemistry Departme nt of Fudan University
Physical ChemistryI Chapter I Introduction of Quantum Mechanics 2021/8/21 Chemistry Department of Fudan University 13 ( , ) exp( / ) 2 3 E T = c1 −c T ( ) ( ) = = − − = 1 1 exp / exp / n n n n n k T k T 3 2 8 ( , ) c E T = = − = 1 1 1 n n x x exp / 1 8 ( , ) 3 2 − = h k T h c E T exp( / ) 8 ( ) 3 3 h k T h c E T ， = c h/ k 2 = h = J s −34 6.63 10 h k T h c E T / 8 ( ) 3 3 ， = Lower Frequency Planck’s Equation Rauleigh-Jeans Equation Higher Frequency ( , ) ( , ) 4 c m T E T =
O Phyical chomitayI Chapter I Introduction of Quantum Meelanics Proble a)Use the fact that JF/(e-1)k=z/15 to show that the radiant energy emitted per second by unit area ofa blackbody is 2kT"/15c"h b The sun's diameter is 1.4x10 m and its effective surface temperature is 5800 K. Assume the sun is a blackbody and estimate the rate ofenergy loss by radiation from the sun. cUse E=mc to calculate the relativistic mass of the photons lose by radiation from the sun in a year 20218/21 Chemistry Departme nt of Fudan University
Physical ChemistryI Chapter I Introduction of Quantum Mechanics 2021/8/21 Chemistry Department of Fudan University 14 Problem: a) Use the fact that to show that the radiant energy emitted per second by unit area of a blackbody is . b) The sun’s diameter is m and its effective surface temperature is 5800 K. Assume the sun is a blackbody and estimate the rate of energy loss by radiation from the sun. c) Use to calculate the relativistic mass of the photons lose by radiation from the sun in a year. /( 1) /15 4 0 3 − = z e dz z 5 4 4 2 3 2 k T /15c h 9 1.410 2 E = mc
O Phyical chomitayI Chapter I Introduction of Quantum Meelanics Radio(Microwave)nfrared(Visible) ultraviolet(xray)Gamma Ray 10 1010 12 Wavelength in centimeters About the size of A 成驶静 Buildings Humans Honey Bee Pinhead Protozoans Molecules Atoms Atomic Nuclei 20218/21 Chemistry Departme nt of Fudan University 15
Physical ChemistryI Chapter I Introduction of Quantum Mechanics 2021/8/21 Chemistry Department of Fudan University 15