ch31_pswc

Diffraction and Interferance __Huygens' Principle__- States every point on a wave front acts as the source of a new wavelet that spreads out in a sphere from that point. Diffraction- If a wave bends because of anything other than reflection or refraction it is called diffraction. Whenever waves pass through an opening or past an edge they will spread, the degree to which they spread will depend on the size of the opening and the wavelength of te waves. When light passes through a large window very little diffraction will be seen, if it passes through a small slit than you wil be able to see a lot of diffracton.


 * __Interference__**- If any two waves arrive in phase with each other they will produce a larger amplitude through constructive interfence,If they are out to phase then they will canel each other through destructive interferance.

A similer patern us observed if the light instead shines on a diffracion grating. The pattern wil be the same as if the light struck a single pair of grooves on the grating.
 * __Young's Interference Experiment-__** when light of one wavelength (monochromatic) shines through two small closley spaced slits it creates a bright and dark pattern.
 * __Single-Color interference from thin films__-** When monochromatic light reflects off of two surfaces that are almost parallel to each other a diffrent set of interfringes wil result.

__**Lazer Light-**__ A beam of light with the same frequency, phase, and direction is said to be oherent. There s no destructive interference between the individual eaves in a bem of coherent light.
 * __Iridescence of thin films-__** The portion of thin-film interference fringes depends on the wavelength of the light illuminating object, as the wavelength of the light increases so does the width of and the spacing between the fringes.

__**The Hologram-**__ a hologram is a hree-dimensional picture of an object that contains an interference pattern generated by spreading a lazer beam so tha half it shines on the object and the other half shines on a piece of film. when the two combind on the film on the film they create an interference pattern.