Aim: How can we explain polarization and dispersion? Do Now: Why do athletes wear polarized sunglasses?

Incoherent Light When light waves emitted by a source have no special phase relationship, the light beam spreads and loses intensity quickly

Coherent Light Monochromatic light with most waves in phase, spreads very little and is intense A laser!!

Light coming from the sun or a light bulb emit light waves that are vibrating in every plane We call this type of light unpolarized

Polarized Light A beam of light that only vibrates in one direction

So what happens if we add a 2nd polarizing filter oriented 90° to the 1st? Demo

What’s Happening?

Only transverse waves (like light) can be polarized Can sound waves be polarized? NO!!!

Dispersion When polychromatic (white) light is passed through a prism, it is separated into its component colors

What is Polychromatic Light?

Which light bends the least? Which light bends the most? red violet

Why? Speed of light inside prism depends on the wavelength of light v = fλ (f is const!!) λred = highest vred = highest Red has the lowest index of refraction, therefore bends the least Violet therefore bends the most

Dispersive Mediums Prisms Air (rainbows) Glass Thin films of: People? Water Bubbles Oil Gas People?

Prism Spectrometer Disperses light into component colors Allows you to determine the elements the stars are made out of when attached to a telescope

Gas Tubes