Electromagnetic Spectrum

What is light? Light is a wave: Light is a particle: Explains much of the everyday behavior of light Light is a particle: Explains why heated objects emit only certain frequencies of light at a given temperature

Light as Waves Wavelength (λ): the shortest distance between equivalent points on a continuous wave. Frequency (v): the number of waves that pass a given point per second. Amplitude: wave’s height from the origin to a crest.

EM spectrum: all forms of electromagnetic radiation often arranged from shortest frequency and wavelength to longest.

Light Math C = speed of light, 3 𝑥 10 8 m/s C = λv Speed of light = wavelength x frequency

Practice What is the frequency of green light, which has a wavelength of 4.9 𝑥 10 −7 m? 3 𝑥 10 8 = 4.9 𝑥 10 −7 x v (3 𝑥 10 8 ) / (4.9 𝑥 10 −7 ) = v V = 6.12 𝑥 10 14

Light as a Particle Quantum: the minimum amount of energy that can be gained or lost by an atom. Proposed by Max Planck He was able to show how quantum was connected to frequency.

E quantum = hv Light Math Quantum energy = Planck's # x frequency Planck’s constant = 6.626 𝑥 10 −34 Js

Practice What is the quantum energy for violet light? Violet light has a frequency of 7.23 𝑥 10 14 . E = (6.626 𝑥 10 −34 )(7.23 𝑥 10 14 ) E = 4.79 𝑥 10 −19

End of Debate In 1905 Einstein proposed that: Light can be thought of as a wave AND Light can be thought of as a stream of tiny particles called ‘photons’. Photon: a particle of electromagnetic radiation with no mass that carries a quantum of energy.

Elemental Light Atomic emission spectrum: the set of frequencies of the electromagnetic waves emitted by atoms of an element. Each element’s atomic emission spectrum is unique and can be used to determine if that element is part of an unknown compound. You can think of the atomic emission spectrum as an element’s fingerprint

Absorbed and Reflected Everything absorbs certain wavelengths of light while reflecting others The colors we see with our eyes are the reflected wavelengths Your assignment is to create an artwork using the absorbed wavelengths of light which will hang in a gallery

Guidelines Your artwork must contain a minimum of 5 colors Red, orange, yellow, green, blue, purple, and any shade in between Black, white, brown, tan do not count as part of the 5 You must write a single-spaced, one page essay to accompany your artwork. It must explain: The basics of the EM Spectrum How an electron’s position results in the characteristic colors of the elements. You will also turn in a paper showing the math calculations for the wavelengths, frequencies and quantum energies for the five colors from your artwork.

Gallery Your artworks will be hung together in a gallery entitled “A New View of Our World: Absorbed Light” There will be instructions included at the beginning of the gallery which explain how to invert the camera colors on your phones to see the traditional reflected colors

How to Invert an IPhone Go to settings Then click on ‘General’ Then click on ‘Accessibility’ Move the switch next to ‘invert colors’ View the following artworks using your cameras!