waves. homework objectives become familiar with the electromagnetic spectrum

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Page 1: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

Waves

Page 2: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

Homework

Page 3: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

Objectives

Become familiar with the electromagnetic spectrum

Page 4: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

Wave Theory: Review

Make waves, check properties

Page 5: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

Wave Properties

The property of a wave isn’t just math to play with, it affects what the wave is and does.

Who remembers: Does anybody know what makes a sound appear to be higher or lower in pitch? What makes it appear louder or softer?

Page 6: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

Wave Properties

The frequency of a sound wave determines whether it’s a high sound or a low sound.

The amplitude of a sound wave determines whether it’s loud or quiet.

Wave properties will be especially important right now to understand about electromagnetic (EM) waves…

Page 7: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

Electromagnetic Waves

Electromagnetic waves are transverse waves. But although they may travel through a medium (or they may not), in EM waves, it’s not the medium that’s oscillating (moving or vibrating). It’s an electrical or magnetic field that is.

Page 8: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

QuickTime™ and a decompressor

are needed to see this picture.

Page 9: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

Electromagnetic waves

Wavelength determines what kind of EM wave it is. (You could also say that frequency does, since they are directly correlated.)

The range of EM wave wavelengths/frequencies is called the electromagnetic spectrum.

Amplitude determines intensity/brightness.

Page 10: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

Electromagnetic spectrum (1st half): http://www.youtube.com/watch?v=kfS5Qn0wn2o

Bill Nye Waves: http://www.youtube.com/watch?v=U-Qsnf-P_5c

Page 11: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

EM Spectrum

Page 12: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

Electromagnetic waves

EM waves are the only tool that we have for studying the universe, but they are a powerful tool that can tell us a lot. Two key pieces of info we can get from a star or other object’s EM waves are what it’s made of, and what direction it’s moving in. Take a moment and talk with your partner, lay out everything you’ve ever heard about Big Bang Theory.

Page 13: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

Big Bang Theory

The Big Bang Theory is the model of the universe best supported by all our current evidence.The universe expanded from a hot primordial condition, and is still expanding today.

Learn about two cool but simple pieces of key evidence from which we figured it out.

Page 14: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

Cosmic Background RadiationWe watched a movie several weeks ago that introduced you to this.Now that you know a bit more about waves, the movie should make more sense.

Rewatch a clip of it, and then you’ll be asked to write a paragraph explaining cosmic microwave background radiation that uses the vocab words I assign.

Page 15: Waves. Homework Objectives Become familiar with the electromagnetic spectrum
Page 16: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

Big Bang Theory

To understand this piece of evidence, a demonstration will help. Be thinking about how to explain what you observe using your knowledge of waves.

Page 17: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

Doppler Effect

The Doppler Effect = the change in frequency & wavelength of a wave for an observer who is moving relative to the wave’s source.

http://www.youtube.com/watch?v=Man9ulEYSgk

Page 18: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

Doppler Effect

It applies to EM waves (including light) as well as to sound and other mechanical waves. If an object is giving off light, and the two of you aren’t perfectly stationary in relation to each other, the wavelengths of the light waves will be longer or shorter depending on who’s moving where. If something is moving towards you, will its color be more blue or more red?

Page 19: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

QuickTime™ and a decompressor

are needed to see this picture.

Page 20: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

Doppler Effect and RedshiftScientists have known for more than 150 years that the light from most stars, nebulas, galaxies, etc. is redshifted, or is more red than it should be. This means that most parts of the universe are moving away from us. When these movements are mapped, it’s clear that this means the universe is expanding.

Page 21: Waves. Homework Objectives Become familiar with the electromagnetic spectrum

Doppler Effect

Draw two diagrams, and write an explanation below each, of how Doppler Shift works for sound, and for light.