A prism, or “ spectrometer ” , splits visible light

A prism, or “spectrometer”, splits visible light ‘white light’ up into its different components

The FULL Electromagnetic

Spectrum

What is doing the “waving”?

An EM wave is a moving self-generating combinationof electric and magnetic fields

Light is like water waves in that it has wavelength and frequency but unlike them in that it needs no medium to move through

direction of propagation of the EM wave

Light As A Particle

Photo-electric effect

E = hc /

What kinds of things emit light?Hot objects – blackbody radiation

– Higher the temperature, the more energy emitted and higher the frequency of light

Examples:

cool dust and gas at 10-1000 K: infrared

surface of sun at 6000 K: visible light

hot gas in corona of sun at 1,000,000 K: X-rays

Atoms – create spectral lines – every atom has its own “spectral signature”

Light is also a particle - photon

Light travels in “packets” of energy, or quanta

E = (h * C) / WavlengthEnergy = constant divided by wavelength

Shorter Wavelength More energy

Light acts like a particle when interacting with matter – absorbed and radiated like particles

Light acts like a wave when traveling, can be bent, reflected, or interfered with, like water waves

Three Kinds of Spectra