Electromagnetic Spectrum

Video EM Intro

Electromagnetic Spectrum

• All electromagnetic waves travel at the same speed, but have different wavelengths and frequencies– Speed = wavelength x frequency– Increase frequency = decrease wavelength– Increase frequency = increase energy– Decrease frequency = increase wavelength

Electromagnetic Spectrum

• Name for the range of electromagnetic waves when placed in order of increasing frequency

• Radio wave – microwaves – infrared rays – visible light – ultraviolet rays – X-rays – gamma rays

Radio Waves

• Long wavelength, low frequency

• Waves are sent out and returned to the source

• Uses:– Radio: the number on your dial is the

frequency

Microwaves

• Shorter wavelength, higher

frequency than radio waves– Can pass through glass and plastic– Reflected off metal– Uses:

• cell phones, RADAR, MRI

Infrared Waves

• Shorter wavelength, higher frequency than microwaves

• Means below red• Snakes can see infrared• Uses:

– Heat rays– Heat bulbs– Thermogram– Camera with night detection

Visible Light

• Shorter wavelength, higher frequency than infrared

• You can see these• Longest wavelength

is red, shortest wavelength is violet– ROY G BIV

Visible Light

• Primary Colors: three colors used to make any other colors (red, blue, and green)

• When combined in equal amounts they will produce white light

Visible Light and Color

• The color of an object is the color of light it reflects, the other colors are absorbed by the light

• Pigments: substances that are used to color other materials, as they are added fewer colors of light are reflected and more are absorbed– When all colors are reflected we see white– When all colors are absorbed we see black– When red, yellow, and blue combine they create black

colors

Ultraviolet Ray

• Shorter wavelength, higher frequency than visible light

• Can damage or kill living cells, causing skin cancer or damage to eyes

• Bees can see UV Rays

The sun’s emission of ultraviolet rays

Ultraviolet Rays

• Uses:– To kill bacteria in hospitals– Small doses are good to acquire vitamin D

which is good for teeth and bones– Treats jaundice in newborns– Tanning beds

X - Rays

• Shorter wavelength, higher frequency than ultraviolet rays

• Can penetrate most objects, but dense bone and lead

• Over exposure can lead to cancer

• Uses– in buildings to find cracks, make pictures of

bones

Gamma Rays

• Shortest wavelength, with highest frequency

• Has the most energy• Most penetrating• Objects in space give off gamma rays, but

our atmosphere protects us against them• Uses:

– Kills cancer cells and can be used to examine the body’s internal structure

Moon in the night sky if you could seegamma rays