Physical+Optics

= Physical Optics = Huygen's principle states that light is has properties that are wavelike. Because light exhibits wavelike properties, every point on the wavefront is the source of waves moving with the same speed which creates a new wavefront. Because of this, diffraction with light becomes possible which is not accounted for by the ray model of light. As light travels through differing mediums, the wavelength and velocity will change. (λ1/λ2=n1/n2) Although the wavelength and velocity change, the frequency remains the same.

Double slit experiment

A single wavelength directed at two narrow slits has two different predictions. The particle theory suggests that two two bright lines will appear on the screen, however, in the wave theory of light, a series of bright and dark parallel lines will appear. This happens because wave interference consisting of constructive(whole number wavelengths) and destructive interference(1/2 number wavelengths). These alternating lines are called fringes. dsin(theta)=mλ

d is the diffraction grating theta is angle that can be measured through simple trig a^2+b^2=c^2 m is (1,2,3......) orders λ is the wavelength of the light

To define lights as colors by wavelength, fλ=c frequencies below less than visible spectrum are infrared, above are ultraviolet between a diffraction grating and two slits, the peaks are much more defined as compared to the slits

Thin films

As light travels through multiple( 2 or more) thin films, part of the light ray reflects and the other is transmitted(goes through) and reflects of the second film. The reflected rays have the potential to constructively and destructively interfere, giving the colors you may see on a bubble or other thin films.

Polarization

Unpolarized light ( no orientation, every which way) can not travel through the "picket fence" or a sheet with many slits Once the light has been polarized, the orientation of the waves are all the same (verticle or horizontal) and when they are in the sam e orientation as the slits, they can shine through as if the slits were not there. The intensity of the plane polarized electromagnetic wave is described as I=Iocos^2(theta0)