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Chapter 13. Section 1 Characteristics of Light. Objectives. Identify the components of the electromagnetic spectrum. Calculate the frequency or wavelength of electromagnetic radiation. Recognize that light has a finite speed.
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Chapter 13 Section 1 Characteristics of Light
Objectives • Identify the components of the electromagnetic spectrum. • Calculate the frequency or wavelength of electromagnetic radiation. • Recognize that light has a finite speed. • Describe how the brightness of a light source is affected by distance.
Characteristics of light What do you think when you think of light? Well when most people think of light , they think of the light they can see What would be some example? Some examples include the bright, white light that is produce by a light bulb or the sun. However there is more to light When you hold a green plastic in front of a source of white light you see green light pass through
Light • What you eyes recognize as white light is actually light that can separated into six elementary colors of the spectrum: • Spectrum can mean the visible spectrum, the range of wavelengths of electromagnetic radiation which our eyes are sensitive to …Spectrum colors are: red,orange,,yellow,green,blue and violet
Light • The realization that visible light is made up of colors is most often attributed to Isaac Newton (though a strong case can be made that it was known well before him), who used a prism to create a spectrum (rainbow of colors) from a beam of white light, and another to recombine them back into white light. And what’s it called when you spread light into a spectrum, for the purpose of studying it (in astronomy, chemistry, …)
Electromagnetic waves • An electromagnetic wave is a wave that consists of oscillating electric and magnetic fields, which radiate outward from the source at the speed of light. • Light is a form of electromagnetic radiation. • The electromagnetic spectrum includes more than visible light.
Light • Not all light is visible to the human eye. If you were to use certain types of photographic film to examine the light disperse through a prism, you would find that the film records to have a much wider spectrum that the one you see.
Electromagnetic waves • Electromagnetic waves vary depending on frequency and wavelength. • All electromagnetic waves move at the speed of light. The speed of light, c, equals c = 3.00 108 m/s • Wave Speed Equation c = f speed of light = frequency wavelen
Example • The AM radio band extends from 5.4 x10^5hz to 1.7x10^6 . What are the longest and shortest wavelengths in this frequency range?
Student guided practice • Do worksheet
Waves • Waves can be approximated as rays. This approach to analyzing waves is called Huygens’ principle. • Lines drawn tangent to the crest (or trough) of a wave are called wave fronts. • In the ray approximation, lines, called rays, are drawn perpendicular to the wave front.
Videos • Let’s watch some videos
Homework • Do problems 1-6 iny our book page 445
closure • Today we learned about light • Next we are going to go over flat mirrors