Electromagnetic Spectrum Use : --- spectra of periodic table of elements

1. The Study of Light The electromagnetic spectrum is the arrangement of electromagnetic radiation according to wavelength. Electromagnetic radiation includes gamma rays, X-rays, ultraviolet light, visible light, infrared radiation, microwaves, and radio waves.

2. Behavior of Light In some instances light behaves like waves, and in others, like particles. In the wave sense, light can be thought of as swells in the ocean. This motion is characterized by a property known as wavelength, which is the distance from one wave crest to the next. Frequency is the number of wave crests that pass a given point in space each second.

Wavelength

A. Characteristics of waves Amplitude = distance from the origin to the crest Wavelength () = distance between adjacent crests Frequency (υ) = number of waves per second

A. Characteristics of waves All waves have a characteristic wavelength, l. Wavelength is measured in nanometers (10-9 m) or meters. The frequency, υ, of a wave is the number of cycles which pass a point in one second. Unit of frequency is 1/s (s-1) or hertz (Hz) Wavelength = lambda Frequency = nu (upper case is N)

Characteristics of waves The speed of a wave, c, is given by its wavelength multiplied by its frequency : For all types of electromagnetic radiation, the speed in vacuum is c = 3.0  108 m/s (also known as the speed of light)

Size of waves 0.5 x 10-6 103 10-2 10-5 10-8 10-10 10-12

Draw what each type of wave looks like below Makes no sense without caption in book

So, a wave with a long wavelength and low frequency = , and a short wavelength and high frequency = The only difference between radio waves, visible light, and gamma-rays is the energy of the photons. Radio and TV waves have low energy, visible light has more energy and gamma waves have the highest energy. TV and Radio waves Gamma waves

Nasa 5 minute video summary

3. Spectroscopy Spectroscopy is the study of the properties of light that depend on wavelength. Types of Spectrums a. Continuous Spectrum • A continuous spectrum is an uninterrupted band of light emitted by an incandescent solid, liquid, or gas under pressure. Incandescent = glowing b/c of heating

3. Spectroscopy Types of Spectrums Look at the overhead lights through the spectroscope and color the spectrum on your paper. Incandescent = glowing b/c of heating

b. Absorption Spectrum An absorption spectrum is a continuous spectrum produced when white light passes through a cool gas under low pressure. The gas absorbs selected wavelengths of light, and the spectrum looks like it has dark lines superimposed.

c. Emission Spectrum An emission spectrum is a series of bright lines of particular wavelengths produced by a hot gas under low pressure. 1. When the spectrum of a star is studied, the spectral lines act as “fingerprints.” These lines identify the elements present and thus the star’s chemical composition.

Emission spectrum Hg Ca Na

Formation of Spectra Makes no sense without caption in book

4. The Doppler Effect a. The Doppler effect is the apparent change in frequency of electromagnetic or sound waves caused by the relative motions of the source and the observer. b. In astronomy, the Doppler effect is used to determine whether a star or other body in space is moving away or toward Earth.

Blue-shift c. If an object is moving towards Earth, the waves are compressed, so their wavelength is shorter. The lines are shifted to shorter (bluer) wavelengths---this is called a blue-shift. Makes no sense without caption in book

Red-shift d. If the object is moving away from Earth, the waves are stretched out, so their wavelength is longer. The lines are shifted to longer (redder) wavelengths---this is called a red-shift. Makes no sense without caption in book

The Doppler Effect Shorter Wavelength = blue shift Longer Wavelength = red shift Makes no sense without caption in book

Doppler effect – sound waves

https://www. youtube. com/watch https://www.youtube.com/watch?v=Tn35SB1_NYI&index=2&list=RDFQqCSpf2vLA

Absorption Spectrum of Our Sun

Add these notes to your TOC At lab you will need: lab sheet Colored pencils spectroscopes