Electromagnetic Spectrum

What is it?

• Name given to a bunch of types of radiation• described as a stream of photons, which are

massless particles each traveling in a wave-like pattern and moving at the speed of light

• Radiation – energy that spreads out as it travels• Hotter, more energetic objects and events create

higher energy radiation• Different waves have different amounts of energy• Moves in transverse wave motion

                  

Gamma Rays

                          

High frequency, Short wavelength0.01 nm

X-Rays

                          

 

                  

1 nm

Ultra-Violet

                          

100 nm

Visible light

                          

400-700 nm

Infra-Red

                          

0.01 mm

Microwaves

                          

1 cm

Radio waves

                           Low frequency,

1 m - 1kmLong wavelength

Radio Waves

• Wavelength – 1mm-100s m • Uses – radio, TV• Make electron in copper wire move = electric

current• AM radio – 187m-545m

– 750 on AM dial is 750 kHz

• FM radio – 2.8 – 3.4 m – 100 on dial is 100 mHz

• TV – 0.4 m – 5.6 m

Microwaves

• 1mm to 1 m

• Wavelength are easily absorbed by water

• Excited water heats up and cooks food

• Cordless phones and cell phones use microwaves– 16 cm –35 cm in wavelength

Infrared

• Wavelength about 1 mm

• “Infra”red =“Below” red light

• Wavelengths longer than red visible light

• Given off by hot objects– Stars, lamps, flames

• Used by remote controls, rescue workers, “night vision,” weather forecasters

• Used by pit vipers to detect prey

Visible light

• Wavelength 700nm – 400nm

• Only part of EM (electromagnetic spectrum) we can detect

• White light actually contain all colors of visible spectrum

                                                               

Ultraviolet

• Ultraviolet = “Above” violet

• 400nm-1000nm

• Visible to insects

• Cause sun damage to skin

• Uses – detect bank forgeries, kill microbes

Normal

Under UV light

                                 

X-Ray

• Wavelength about 1 nm

• High energy, short wavelength– They can go right through you, but not bones

• Uses – evaluating bodily injuries, airport security

• Can cause cell damage and cancer

Gamma Rays

• High frequency will go through metal– Need lead or thick concrete to stop them

• Can cause cancer

• Uses- radio-therapy to treat cancer, evaluate stability of airplane wings, “irradiate” food

Conclusion

• Longer wavelength = less energy

• More energy = greater penetrating power (more danger)

• To see all parts of EM you need to go to space

• Stars give off all types of EM