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10/9 - 7 th Grade Agenda. Payday Collect: HW: p.33- 34 Waves and Electromagnetic Spectrum Class Reading: p. 42- 44 HW: Workbook: p. 35- 36. Electromagnetic Wave. An electromagnetic wave consists of vibrating electric and magnetic field that move through space at the speed of lig____. ht.
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10/9 - 7th Grade Agenda Payday Collect: HW: p.33- 34 Waves and Electromagnetic Spectrum Class Reading: p. 42- 44 HW: Workbook: p. 35- 36
Electromagnetic Wave • An electromagnetic wave consists of vibrating electric and magnetic field that move through space at the speed of lig____ ht
What are some examples of electromagnetic waves? • Radio Waves • TV Signals • Microwaves • Infrared rays • Light • Ultraviolet rays • X-Ray
How fast do electromagnetic waves travel? • It is the fastest thing in the universe • 300,000 km per second • 186,000 miles per second • It takes 8 minutes for light to travel from the sun to the earth • It takes 3 million years for light to travel from the nearest galaxy (andromeda) to the earth
How do we use Radio Waves? • Radio & TV signals • Microwave Oven • Radar • MRI • Cell phone
Using Microwaves • Why do you see sparks you put metal objects in a microwave? • Because of the build up of electrical energy in the metal • The long wave length of Microwaves can pass right through glass and plastic. That is why microwaves do not heat glass and plastic containers.
How do we use Infrared Rays? • Conventional Oven • Heat Lamps • Thermograms
Visible Light makes up only a small part of the electromagnetic spectrum
Wave • A wave is a disturbance that transfer ene_____ from place to place. • Who can give me examples of waves? rgy
Is light a wave? • Yes • But why?
Picture of Light Wave • Image of a pulse of light that is 2.5 billionths of a millionth of a second long
Energy • In science, energy is defined as the ability to do wo___. rk
Medium • The material through which a wave tra____ is called a medium • Who can give me examples of medium? vels
Does Light Waves need a medium? • Scientist first thought that Light needed to travel through a medium. So they invented the idea of aether in space. • They look for aether in outer space but they found nothing. • So, Light Waves can travel without a medium even in a Vacuum of outer space.
Crest gh • Hi___ point of a wave is called a crest
Trough ow • L___ point of a wave is called a trough
Amplitude imum • Amplitude is the max______ distance that the particles of medium carrying the wave move away from their rest positions. • Which rope has higher amplitude?
Wavelength • The distance between two corresp______ parts of a wave is its wavelength. • Which rope has longer wavelength? onding
Frequency • Wave frequency is the num_____complete waves that pass a given point in a certain amount of time ber