Blackbody Radiation Black Body Radiation An ideal blackbody

Blackbody Radiation

Black Body Radiation • An ideal blackbody is a physical body that absorbs all incident electromagnetic radiation. • If the blackbody is in thermal equilibrium it will do the following: • It emits as much or more energy than any other physical body at its temperature • It emits radiation isotropically (independent of direction)

Black Body Radiation • A black body in thermal equilibrium emits electromagnetic radiation called black-body radiation. • The spectrum of a blackbody can be used to determine its temperature

Black-Body Graph •

Spectra • Using a diffraction grating will break white light up into spectra. The spectra are made by photons with a particular wavelength (color) • There are three types of spectra • Emission – only see bands of color, made by an excited gas (translucent) • Continuous – see all colors, made by an opaque object • Absorption – see all colors with black lines corresponding to absorption, where a gas is absorbing those photons which make those black lines

Emission Spectra • A gas will emit photons corresponding to colors. The photons come from the electrons in the atoms of the gas jumping levels because of certain amounts of energy. • The energy required to go from one orbit to another is QUANTIZED! Hence we have Quantum Mechanics.

Absorption Spectra • Stars are approximately black bodies, except they are missing a very wavelengths, because of absorption • Graphing a star’s Intensity vs Wavelength will show dips, which correspond to absorption

Absorption Spectra •

Spectrum Lab • You remember some of the elements here from chemistry, now do the physics version of this lab. • This will be a whopping 70 pts. YOU HAVE TO TURN THIS LAB IN AS SOON AS POSSIBLE!! DUE DATE: 3/17 3 RD QUARTER APPROACHES SOON! YOU ARE AN HONORS STUDENT, NO EXCUSES!!!