Section 2

Question 1

Young’s double slit from phase differences between the two paths; can write as a sum of two complex waves:

Answer 1

Ψ = Ψ1 + Ψ2 = |Ψ1|e^(iα1) + |Ψ2|e^(iα2)

Question 2

intensity is given by mod-square of the amplitude (formula)

Answer 2

I = |Ψ|^2 = Ψ*Ψ

Question 3

I = |Ψ1+Ψ2|^2 (derivation)

Answer 3

I = |Ψ1+Ψ2|^2

I = |Ψ1|^2 + |Ψ2|^2 + Ψ1Ψ2+Ψ2Ψ1

I = |Ψ1|^2 + |Ψ2|^2 + 2Re{Ψ1Ψ2*}

I = |Ψ1|^2 + |Ψ2|^2 + 2|Ψ1Ψ2|cos(α1-α2)

banded pattern comes from the phase-interference term

Question 4

Bohr’s principle of complementarity

Answer 4

repeat the classic wave interference experiment with electron beams => interference pattern

try to identify which slit the electron passes through: pattern disappears