SME
College · Science
Quantum Mechanics
5 topics
Physics
Before this course
Topics
Wavefunctions and operators
Main lesson
Uncertainty in a box: ⟨x⟩, Δx and Δp
Use this for “An electron is in state n = 2 of a 0.5 nm box. Find ⟨x⟩, Δx and Δp, and check the uncertainty principle.”
Measuring the energy of a superposition
Use this for “A particle in a box is in the state 3ψ₁ + 4ψ₂, with E₁ = 0.2 eV. What energies can a measurement give, with what chances, and what is ⟨E⟩?”
Which observables commute?
Use this for “Can the position x and the momentum pᵧ of an electron both be known exactly at once?”
Solving the Schrödinger equation
Main lesson
The quantum harmonic oscillator
Use this for “A molecule vibrates at ω = 5.6 × 10¹⁴ rad/s. Find its zero-point energy, the energy of level n = 2 and the wavelength of the photon of one step down.”
Tunneling through a barrier
Use this for “An electron meets a barrier 0.3 eV above its energy and 1.2 nm wide. Estimate the chance that it tunnels through.”
Reflection at a potential step
Use this for “Electrons of 9 eV meet a potential step 5 eV high. What fraction is reflected, and what fraction goes on?”
Angular momentum and spin
Main lesson
Measuring spin along a tilted axis
Use this for “An electron leaves a Stern–Gerlach magnet spin up along z and enters a second magnet tilted 120° from z. Find the chances of up and down and the average reading.”
Zeeman splitting and spin resonance
Use this for “An atom in a p state (ℓ = 1) sits in a 0.5 T field. How far apart are its levels, how many are there, and at what frequency does a free electron’s spin flip?”
Adding two angular momenta
Use this for “A d electron has ℓ = 2 and spin s = ½. Which total j can it have, how many states does each hold, and how many states are there in all?”
Perturbation theory
The hydrogen atom
Main lesson
The chance the 1s electron is within R
Use this for “What is the chance of finding hydrogen’s ground-state electron within one Bohr radius of the nucleus?”
Hydrogen-like systems with a moving nucleus
Use this for “Find the ground-state energy of muonic hydrogen (a muon, 206.8 mₑ, round a proton).”
Course test
See what you know: 10 questions on this course
New questions each time. Pass to mark it complete.