continuous spectra -- blackbody rad’n
Common examples of heated solid or liquid
- incandescent light bulb
- Edison built the first ones
- tungsten filament heated to 2800 K
- highest temperature before melting
- peak wavelenth 1000 nm, which is not visible
- continuous spectrum includes visible red, green, blue
- demo with vu-graph projector
- slit gives collimated light
- prism separates the wavelengths (colors)
- blue bent the most, red the least
- same principle as the rainbow
- Newton used prisims to investigate nature of sunlight
- diffraction grating also separates light
- based on intereference of light waves
- constructive and destructive -- draw waves on blackboard
- gives soap bubbles colors
- blue bent the least, because it has the shortest wavelength