Question

1. The shorter the wavelength of a photon, the more the photon behaves like a particle. Why?

2. In a H2 molecule there are two protons, and these have spin 1/2 ħ, that is, they are fermions. If we just look at the two protons, would you expect their spins to be parallel or anti parallel in the ground state of the H2 molecule?

3. Is there a type of viscosity that acts on holes in a semiconductor and gives them a terminal velocity in an electric field, or do holes just accelerate under the influence of such a field? If there is a terminal velocity, is it the same as that of the electrons?

4. For what kinetic energy is the de Broglie wavelength of an electron equal to its Compton wavelength? Express your answer in units of mc2 in doing the calculation, and then use mc2 = 0.5 MeV.(Answer: 0.2 MeV)

5. A beam of electrons with energy 1.0 eV approaches a potential barrier with U = 2.0 eV, whose width is 0.10 nm (see a figure below). Estimate the fraction of electrons that tunnel through the barrier. (Hint: use the relation of probability and the wave function, and the expression for wave function for barrier penetration)

6. Calculate the Fermi energy of sodium (n= 2.65·10^28 m^-3). This metal has a single valence electron per atom.(Answer: 3.25 eV.)

Answer 1