Questions from Modern Physics

Q: The assumptions of the free-electron model of metals may seem

The assumptions of the free-electron model of metals may seem contrary to reason, since electrons exert powerful electric forces on each other. Give some reasons why these assumptions actually make ph...

Q: Why are materials that are good thermal conductors also good electrical conductors

Why are materials that are good thermal conductors also good electrical conductors? What kinds of problems does this pose for the design of appliances such as clothes irons and electric heaters? Are t...

Q: What is the essential characteristic for an element to serve as a

What is the essential characteristic for an element to serve as a donor impurity in a semiconductor such as Si or Ge? For it to serve as an acceptor impurity? Explain.

Q: There are several methods for removing electrons from the surface of a

There are several methods for removing electrons from the surface of a semiconductor. Can holes be removed from the surface? Explain.

Q: It can be a challenge to solve the Schrödinger equation for the

It can be a challenge to solve the Schrödinger equation for the bound-state energy levels of an arbitrary potential well. An alternative approach that can yield good approximate results f...

Q: The WKB approximation (see Challenge Problem 40.64) can

The WKB approximation (see Challenge Problem 40.64) can be used to calculate the energy levels for a harmonic oscillator. In this approximation, the energy levels are the solutions to the equation....

Q: Protons, neutrons, and many other particles are made of more

Protons, neutrons, and many other particles are made of more fundamental particles called quarks and antiquarks (the antimatter equivalent of quarks). A quark and an antiquark can form a bound state w...

Q: How could you make compensated silicon that has twice as many acceptors

How could you make compensated silicon that has twice as many acceptors as donors?

Q: Each of 2N electrons (mass m) is free to move

Each of 2N electrons (mass m) is free to move along the x-axis. The potential-energy function for each electron is U(x)= 1/2 k′x2, where k′ is a positive constant. The electric and magnetic interactio...

Q: Consider a simple model of the helium atom in which two electrons

Consider a simple model of the helium atom in which two electrons, each with mass m, move around the nucleus (charge +2e) in the same circular orbit. Each electron has orbital angular momentum Ä&...