From 86f09bcfaa1e4ef48cbac8bd45a4ada9d4be67fc Mon Sep 17 00:00:00 2001 From: othocaes Date: Thu, 28 Apr 2016 16:51:34 -0400 Subject: [PATCH] lots of lectures. Class is now over. --- lecture_notes/4-13/overview | 43 +++++++++++++++++++++++++++++++ lecture_notes/4-15/Overview | 50 +++++++++++++++++++++++++++++++++++++ lecture_notes/4-18 | 6 +++++ solutions/chap2/prob2 | 30 ++++++++++++++++++++++ solutions/chap3/prob7 | 3 +++ 5 files changed, 132 insertions(+) create mode 100644 lecture_notes/4-13/overview create mode 100644 lecture_notes/4-15/Overview create mode 100644 lecture_notes/4-18 create mode 100644 solutions/chap2/prob2 create mode 100644 solutions/chap3/prob7 diff --git a/lecture_notes/4-13/overview b/lecture_notes/4-13/overview new file mode 100644 index 0000000..77d788f --- /dev/null +++ b/lecture_notes/4-13/overview @@ -0,0 +1,43 @@ + Exam 2 Problem 2 +━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ + +(pic) Finished the problem using the boundary conditions + + boundary conditions limit the number of possible spherical harmonics. + + + + Two Similar Particles +━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ + +❙a,b❭ = ❙a❭⊗❙b❭ + + Exchange Operator +────────────────────────────────────────────────────────────────────────── + +𝓟₁₂❙a,b❭ = ❙a,b❭ + +𝓟₁₂(❙a❭⊗❙b❭) = ❙b❭⊗❙a❭ + +If particles are indistinguishable + +𝓟₁₂❙a,b❭ = exp(iδ) ❙a,b❭ = λ ❙a,b❭ + +𝓟²₁₂❙a,b❭ = λ² ❙a,b❭ = ❙a,b❭ ⇒ λ=±1 + + + Symmetry States +────────────────────────────────────────────────────────────────────────── +(pic) Two cases: symmetric, antisymmetric + +Symmetric States, λ=1 + + 𝓟₁₂❙a,b❭ + +(pic) Constructed the exchange operator in matrix form, then found eigen states + +(pic) Showed that the exchange operator leads to the Pauli Exclusion Principle + + + + diff --git a/lecture_notes/4-15/Overview b/lecture_notes/4-15/Overview new file mode 100644 index 0000000..81b1ec2 --- /dev/null +++ b/lecture_notes/4-15/Overview @@ -0,0 +1,50 @@ + Two Spin-½ Particles +━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ +uncoupled basis +─────────────── +❙s₁ s₂ m₁ m₂❭ +❙+ +❭, ❙- -❭, ❙+ -❭, ❙- +❭ + +coupled basis +───────────── +❙S Mₛ❭ +❙1 1❭, ❙1 -1❭, ❙1 0❭, ❙0 0❭ + +Given the state ❙1 0❭ = 1/√2(❙+ -❭ + ❙- +❭) : + P₁₂❙1 0❭ = ❙1 0❭ (symmetric) + +❙0 0❭ = 1/√2(❙+ -❭ - ❙- +❭) : + P₁₂❙0 0❭ = -❙0 0❭ (antisymmetric) + + + Spatial Representation +────────────────────────────────────────────────────────────────────────── +❙Ψ❭ = ❙Ψₛₚₐₜᵢₐₗ❭❙Ψₛₚᵢₙ❭ + +Symmetric: +❙Ψ❭ˢ = ❙Ψₛₚₐₜᵢₐₗ❭ˢ❙Ψₛₚᵢₙ❭ˢ OR ❙Ψₛₚₐₜᵢₐₗ❭ᴬ❙Ψₛₚᵢₙ❭ᴬ + +Antisymmetric: +❙Ψ❭ᴬ = ❙Ψₛₚₐₜᵢₐₗ❭ᴬ❙Ψₛₚᵢₙ❭ˢ OR ❙Ψₛₚₐₜᵢₐₗ❭ˢ❙Ψₛₚᵢₙ❭ᴬ + + + Helium Atom +────────────────────────────────────────────────────────────────────────── +Fermions, so overall must be antisymmetric + +Configuration Term Energy + 1s² 1s 0 + ❙Ψ❭ = 1/√2 (❙a❭₁ₛ❙b❭₁ₛ + ❙b❭₁ₛ❙a❭₁ₛ)❙0 0❭ + + 1s²s 3s 1.46 + ❙Ψ❭ = 1/√2(❙a❭₁ₛ❙b❭₁ₛ - ❙b❭₁ₛ❙a❭₁ₛ)❙1 m❭, m=-1,0,1 + + 1s2s 1s 1.52 + ❙Ψ❭ = 1/√2 (❙a❭₁ₛ❙b❭₁ₛ + ❙b❭₁ₛ❙a❭₁ₛ)❙0 0❭ + + 1s2p 3pᵒ ~1.60 + ❙Ψ❭ = 1√2 + + 1s²p 1pᵒ ~1.65 + + diff --git a/lecture_notes/4-18 b/lecture_notes/4-18 new file mode 100644 index 0000000..1294537 --- /dev/null +++ b/lecture_notes/4-18 @@ -0,0 +1,6 @@ +∮𝐁⋅d𝐥 = B(s) sπs = μ₀[∫𝐉⋅n̂da + ε₀ d/dt ∫𝐄⋅n̂da] + +∫𝐉⋅n̂da = 0 + +For capacitor: +│𝐄│ = σ/ε₀ ⇒ B(s) 2πs = μ₀ ε₀ d/dt σ(t)/ε₀ πs² \ No newline at end of file diff --git a/solutions/chap2/prob2 b/solutions/chap2/prob2 new file mode 100644 index 0000000..9e06ed7 --- /dev/null +++ b/solutions/chap2/prob2 @@ -0,0 +1,30 @@ +S𝓍 ≐ ħ͟⎛0 1⎞ + 2⎝1 0⎠ + +Diagonalize the matrix... + +First, find the characteristic equation and solve for the eigenvalues. + +S𝓍 ≐ ħ͟⎛0 1⎞ + 2⎝1 0⎠ + +ħ͟ ⎛-λ 1⎞ +2 ⎝ 1 -λ⎠ + + λ² - ħ²/4 = 0 + λ² = ħ²/4 + + λ = ±ħ/2 + +So the eigenvalues are those expected for the measurement of a spin-1/2 component. + +The eigenvalue equations are + +S𝓍❙Ψ❭ = λ❙Ψ❭ + +which is represented by + +ħ͟⎛0 1⎞⎛a⎞ = λ⎛a⎞ +2⎝1 0⎠⎝b⎠ ⎝b⎠ + + diff --git a/solutions/chap3/prob7 b/solutions/chap3/prob7 new file mode 100644 index 0000000..ba929af --- /dev/null +++ b/solutions/chap3/prob7 @@ -0,0 +1,3 @@ +After the first Stern-Gerlach magnet, the entire wave function will be in a single state: + +❙Ψ₁❭ = ❙S₊❭ \ No newline at end of file