Question

1-Recall the expression of thermal conductivity.

2-Recall the expression for electron energy levels in One dimension.

3-Give a comparison between ferromagnetic, antiferromagnetic and paramagnetic materials.

Answer 1

1. Recall the expression of thermal conductivity.

2-Recall the expression for electron energy levels in One dimension.

The square of the normalized wave function |ψ_n(x,t)|² = |ψ_n(x)|² = A_n²sin²(nπx/L) is equal to the probability per unit length of finding the particle with energy E_n at position x. To normalize the wave function we have to choose A_n² = 2/L. Then ∫_-∞^+∞|ψ(x,t)|²dx = 1, and the total probability of finding the particle inside the well is 1.

3. Give a comparison between ferromagnetic, antiferromagnetic and paramagnetic materials.

Paramagnetism refers to materials like aluminum or platinum which become magnetized in a magnetic field but their magnetism disappears when the field is removed.
Ferromagnetism refers to materials (such as iron and nickel) that can retain their magnetic properties when the magnetic field is removed.

In materials that exhibit antiferromagnetism, the magnetic moments of atoms or molecules, usually related to the spins of electrons, align in a regular pattern with neighboring spins (on different sublattices) pointing in opposite directions.