Title: Summary Electrical and Thermal Properties of Metals

Choose the correct statement.

- Ohm's Law states that the resistance is independent of the applied voltage. (correct)
- Ohm's Law states that the resistivity depends on the current density.

- In the Drude model we assume that electrons are classical particles and that they do not interact with each other either through collision or because of their charges. They only interact with ions by collisions like billiard balls. (correct)
- In the Drude model electrons are treated like classical particles, which do not interact with each other because of their charges. They only interact through electron-electron collisions or with the positive ions like billiard balls.

- Classical free electron theory predicts ohmic behaviour! The drift velocity is linearly proportional to the electric field, and therefore we know that the conductivity is a constant value. (correct)
- Ohmic behaviour cannot be explained by classical free electron theory. The thermal velocity is dependent of the electric field, which contradicts Ohm's Law.

- Hall effect measurements and real data from heat capacity values show the limits of the Drude model in explaining these two properties. (correct)
- The Drude model always shows a good agreement with Hall effect measurements, but it overestimates the heat capacity of metals by a factor 100.

- In the Free Electron Fermi Gas model, electrons do not interact with each other or with ions, but they are described by quantum mechanics (Schrödinger equation and Pauli Principle). (correct)
- In the Free Electron Fermi Gas model, electrons interact with each other and with ions, and they are described by quantum mechanics (Schrödinger equation and Pauli Principle).

- The Density of States D(E) is defined as the number of states per unit energy range. (correct)
- The Density of States D(E) is defined as the number of states per unit temperature range.

- The density of states D(E) for free electrons in 3 dimensions increases with the square root of the energy. (correct)
- The density of states D(E) for free electrons in 3 dimensions increases quadratically with the energy.

- The Fermi energy is the energy corresponding to the highest occupied electronic state at zero kelvin. (correct)
- The Fermi energy is the energy corresponding to the highest possible electronic state at zero kelvin.

- The calculated QM free electron values for Fermi energies correspond quite well to the measured values except for the elements Si and Mg. (correct)
- The calculated QM free electron values for Fermi energies correspond quite well to the measured values except for the elements Na and Li.

- The Fermi-Dirac distribution defines the probability that an orbital at energy E will be occupied at thermal equilibrium. (correct)
- The Fermi-Dirac distribution defines the fraction of QM free electrons that are excitable by thermal energy.

- The real heat capacity data corresponds well to the calcaluated data using the QM free electron model for metals but not for insulators. (correct)
- The real heat capacity data corresponds well to the calcaluated data using the QM free electron model for insulators but not for metals.

- Although the Free Electron Fermi Gas model explains more properties than the classical model, interactions with the lattice will have to be included in order to make progress. (correct)
- Although the Free Electron Fermi Gas model explains more properties than the classical model, electron-electron interactions will have to be included in order to make progress.