Light

Chapter 14

Just like the falling rainbow,Just like the stars in the sky,Life should never feel small.

-Vearncombe

Objectives of Section 14-1:

• Identify the components of the electromagnetic spectrum.

• Calculate the frequency or wavelength of an e-wave.

• Recognize that light has a finite speed.

Electromagnetic Waves*e-waves*

• E-waves are waves which are

capable of traveling through a vacuum.

• E-waves vary depending on

frequency and wavelength.

• All e-waves travel at the

same speed: c = 3 x 108 m/s

e-waves…

• Electromagnetic waves are formed when an electric field (which is shown in blue arrows) couples with a magnetic field (which is shown in red arrows).

The Electromagnetic Spectrum

• The electromagnetic spectrum includes, from longest wavelength to shortest: radio waves, microwaves, infrared, optical, ultraviolet, X-rays, and gamma-rays.

Radio Waves

• Radio waves have the longest wavelengths in the e-spectrum.

• The antennae on your television set and cell phones receive the signal, in the form of e-waves.

Microwaves

• microwaves are good for transmitting information from one place to another.

• RADAR - RAdio Detection And Ranging.

• Radar is a system that uses radio waves to determine and map the location, direction, and/or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations and terrain

Radar

• Radar is a system that uses radio waves to determine and map the location, direction, and/or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations and terrain

Infrared

• Infrared light is even used to heat food sometimes-special lamps.

• remote control.

• The heat that we feel

from sunlight, a fire, a

radiator or a warm

sidewalk is infrared.

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Infrared Waves, continued.

• Humans, at normal body temperature, radiate most strongly in the infrared.

• To make infrared pictures like the one above, we can use special cameras and film that detect differences in temperature

Visible Light Spectrum

• ROY G BIV

• Visible light waves are the only electromagnetic waves we can see.

Visible Spectrum, con’t.

• Rainbow

• When white light shines through a prism or through water vapor like this rainbow, the white light is broken apart into the colors of the visible light spectrum.

Prism

• When white light, such as sunlight passes through a prism, it is refracted in the colors of the rainbow.

Ultraviolet Waves

• Though these waves are invisible to the human eye, some insects, like bumblebees, can see them.

• Sterilization of medical instruments.• Identification of fluorescent minerals.• Sun emits light at all the different

wavelengths in electromagnetic spectrum, but it is ultraviolet waves that are responsible for causing our sunburn

X-Rays

• Medical examination of bones, teeth and vital organs.

• Treatment of types of

cancer.

Gamma Rays

• Examination of thick materials of structural flaws.

• Treatment of types of cancer.

• Food irradiation.