Questions from Modern Physics

Q: In the ground state of the helium atom one electron must have

In the ground state of the helium atom one electron must have “spin down” and the other “spin up.” Why?

Q: An electron in a hydrogen atom is in an s level,

An electron in a hydrogen atom is in an s level, and the atom is in a magnetic field B = B

Q: Consider a system of N free electrons within a volume V.

Consider a system of N free electrons within a volume V. Even at absolute zero, such a system exerts a pressure p on its surroundings due to the motion of the electrons. To calculate this pressure, im...

Q: When the pressure p on a material increases by an amount ∆

When the pressure p on a material increases by an amount ∆p, the volume of the material will change from V to V + ∆V, where ∆V is negative. The bu...

Q: What factors determine whether a material is a conductor of electricity or

What factors determine whether a material is a conductor of electricity or an insulator? Explain.

Q: Consider a collision in which a stationary particle with mass M is

Consider a collision in which a stationary particle with mass M is bombarded by a particle with mass m, speed v0, and total energy (including rest energy) Em. a. Use the Lorentz transformation to wri...

Q: Speeds of molecules in a gas vary with temperature, whereas speeds

Speeds of molecules in a gas vary with temperature, whereas speeds of electrons in the conduction band of a metal are nearly independent of temperature. Why are these behaviors so different?

Q: Use the band model to explain how it is possible for some

Use the band model to explain how it is possible for some materials to undergo a semiconductor-to-metal transition as the temperature or pressure varies.

Q: An isolated zinc atom has a ground-state electron configuration of

An isolated zinc atom has a ground-state electron configuration of filled 1s, 2s, 2p, 3s, 3p, and 4s subshells. How can zinc be a conductor if its valence subshell is full?

Q: For the particle in a box, we chose k = nπ

For the particle in a box, we chose k = nπ/L with n = 1, 2, 3, …………. to fit the boundary condition that Ψ = 0 at x = L. However, n = 0, -1, -2, -3, …… also satisfy that boundary condition. Why didn’t...