updated: April 2007

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Unit 3: The Wave Nature of Light

In the previous physics course, we looked at refraction and geometric optics. Light behaved like a ray or beam of particles. Here we begin the transition from classical physics to modern/quantum physics. In this unit we will look at more unusual properties of light and see that the more we learn, the more complicated it gets. These bizarre characteristics of light lead to all sorts of important practical applications: lasers, LCDs, anti-reflection coatings, ...

Unit Objectives

Note: we don't have any textbooks that clearly cover all of these topics. A combination of Giancoli, Nelson and Martindale would be best.



Textbook pages & other resources


1. Intro & review
definitions of wave teminology
chapter 23  
2. Wave-Particle Controversy p679-681  
3. Two Source Interference
|PS2-PS1| = nl (lambda)
not in Giancoli  
4. Young's Double Slit Diffraction & Interference
nl = d sinq
682-685, 689-691  
5. Lab: diffraction using lasers  
6. Polarization, LCDS.
Handout on Lasers
7. Thin Films 694-697  
8. Thin Films (continued) [summary]    
9. Production of light; spectra.
10. Unit Test

Unit Objectives

By the end of this unit the student will be able to:

  • define and explain these concepts:
    diffraction, polarization, interference, dispersion, electromagnetic radiation, electromagnetic spectrum
  • state the regions of the electromagnetic spectrum in order (by energy or wavelength)
  • explain how electromagnetic radiation is produced
  • list evidence to support the wave theory of light
  • list evidence to support the particle nature of light
  • name one property of light that the wave theory fails to explain
  • name one property of light that the particle theory fails to explain
  • use the inverse-square law to compare light intensities at two different distances and to calculate the intensity of light at a given distance from a source of specified power
  • calculate locations of interference maxima or minima based on source frequency for two sources separated by a certain distance. |PS1 PS2| = n(lambda)
  • sketch the pattern of single and double slit diffraction of light
  • apply the formulas for single and double slit diffraction to determine the locations of maxima and minima. n(lambda) = dsin(theta)
  • explain the advantage of a diffraction grating over a double slit grating
  • explain how thin-film interference works
  • determine the thickness of a thin film used to reflect or transmit light of a certain wavelength
  • explain how lasers work, using the terms: metastable, stimulated emission, population inversion, coherence.
  • explain how LCDs work.
  • The following objectives from the previous physics course are also required:

  • apply the Universal Wave Equation to light (and other forms of electromagnetic radiation)
  • define index of refraction and use it to calculate the speed of light in various media