Dr.Eman Zakaria Hegazy Quantum Mechanics and Statistical Thermodynamics Lecture7
Revision
1. Radiation in the ultraviolet region of the electromagnetic
spectrum is usually described in terms of wavelength λ,
and is given in angstrom units (1 Å = 10-10 m) or nanometer
(10-9 m). Calculate ν,  and E for ultra violet radiation with
λ = 2000 Å.
2. At what wavelength does the maximum in the energydensity distribution function for a blackbody occur if (a)
T=300 K? (b) T=3000K?
3. Using the values of k, h and c , calculate the value of the
Stefan –Boltzmann constant and compare it to the
experimental value, 5.670x10-8 J.m-2.k4.s-1.(k=1.38 x10-23
J.K-1, h=6.626x10-34J.s and c= 3x108m.s-1
4. When a clean surface of silver is irradiated with light of
wavelength 230nm, the stopping potential of the ejected
electrons is found to be 0.80V. Calculate the work function
and the threshold frequency of silver.
5. Define : Blackbody radiation, photoelectric effect, emission
spectrum, threshold frequency, stopping potential