Diffraction & Interference (Light)

Discussion

The bending or spreading of light through an opening or around an obstacle.

Goethe "flexibility of light"

Why is it possible to hear around corners, but not see around them?

Diffraction of laser light through a vertical opening of decreasing width. Note that as the opening gets narrower, the amount of diffraction in the horizontal direction increases. (The interference fringes will be dealt with in a later section of this book.) This image sequence is also available as an animated gif.

double source interference

text

[need pic]

Double source interference. Laser light through two closely spaced slits.

multiple source interference (diffraction grating)

Multiple source interference. Laser light through a diffraction grating.

single source interference (self interference)

Single source interference. Laser light through a narrow opening.

spectroscopy

continuous vs. discrete

Continuous: temperature from Wien's Displacement Law

Discrete: "bar codes" of the elements

The continuous spectrum of daylight. Note the absence of any significant gaps.

The discrete spectrum of excited mercury vapor.

The discrete spectrum of excited helium gas.

The discrete spectrum of a fluorescent light. These spectral lines are wider since they came from a wider source.

Quotes that need to be paraphrased.