title: Diffraction
author: David M. Williamson
description: When not writing fantasy and science fiction, David Williamson is a U.S. Air Force enlisted aircrew flyer with over twenty years on active duty. He won NaNoWriMo twice and published his 2014 novel, Not to the Swift. The 2015 novel is in revision. David also has five short personal stories included in God Still Leads and Guides, a compilation by Mark Littleton. And David has a book on writing, Elements of Critique, covering 30 subjects based on his positive experiences and lessons learned in a critique group. David is a husband to his amazing wife Jami and a father of four wild children ranging from toddler to teens. He is also a Christian songwriter, worship leader, pianist, and coffee fiend.
zlib_text: Ch. 36   p. 1 
   
  CHAPTER 36 – Diffraction and Polarization 
   
  1. 
  We find the angle to the first minimum from 
   
   
  sin θ1min = mλ/a = (1)(680 × 10–9 m)/(0.0345 × 10–3 m) = 0.0197, so θ1min = 1.13°. 
   
  Thus the angular width of the central diffraction peak is 
   
   
  ?θ1 = 2θ1min = 2(1.13) =      2.26°. 
   
  2. 
  The angle from the central maximum to the first minimum is 18.5°. 
   
  We find the wavelength from 
   
   
  a sin θ1min = mλ; 
   
   
  (3.00 × 10–6 m) sin (18.5°) = (1)λ, which gives λ = 9.52 × 10–7 m =      952 nm. 
   
  3. 
  For constructive interference from the single slit, the path difference is 
   
   
  a sin θ = (m + !)λ,   m = 1, 2, 3, … . 
   
  For the first fringe away from the central maximum, we have 
   
   
  (3.50 × 10–6 m) sin θ1 = (*)(550 × 10–9 m), which gives θ1 = 13.7°. 
   
  We find the distance on the screen from 
   
   
  y1 = L tan θ1 = (10.0 m) tan 13.7° =     2.4 m. 
   
  4. 
  The angle from the central maximum to the first bright fringe is 19°. 
   
  For constructive interference from the single sl