Electromagnectic Spectrum

Electromagnectic Spectrum1Electromagnetic SpectrumIn 1852, James Clerk Maxwell proved that visible light was part of a larger spectrum.Each color of visible light is a different wavelength of electromagnetic radiation.Humans can see radiation from Red (longest) through to Violet (shortest).Visible light is only a small part of the Electromagnetic Spectrum. Lucky for us, most of the invisible radiation can not pass through our atmosphere.

2Nature of Electromagnetic WavesThey are Transverse waves without a medium. (They can travel through empty space)They travel as vibrations in electrical and magnetic fields.Speed of electromagnetic waves = 300,000,000 meters/second-

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Waves of the Electromagnetic SpectrumRadio WavesMicrowavesInfrared RaysVisible LightUltraviolet RaysX-RaysGamma Rays4RADIO WAVESA. Have the longest wavelengths and lowest frequencies of all the electromagnetic waves.B. A radio picks up radio waves through an antenna and converts it to sound waves.C. Each radio station in an area broadcasts at a different frequency. # on radio dial tells frequency.D. MRI (MAGNETIC RESONACE IMAGING)Uses Short wave radio waves with a magnet to create an image

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MRI of the Brain

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Amplitude modulation (AM) waves bounce off ionosphere that is how you can pick up stations from different cities.(535kHz-1605kHz= vibrate at 535 to 1605 thousand times/second)

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Frequency modulation (FM)waves travel in a straight line & through the ionosphereyou lose reception when you travel out of range.(88MHz-108MHz = vibrate at 88million to 108million times/second)

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Examples

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MICROWAVESMicrowaveshave the shortest wavelengths and the highest frequency of the radio waves.Used in microwave ovens.Waves transfer energy to the water in the food causing them to vibrate which in turn transfers energy in the form of heat to the food.Used by cell phones and pagers.RADAR (Radio Detection and Ranging)Used to find the speed of an object by sending out radio waves and measuring the time it takes them to return.10

To get around the problem of the dense cloud layer, Magellan viewed the surface of Venus using microwave radiation. Microwave radiation is a type of light with longer wavelength than visible light. Microwave radiation is able to penetrate the cloud layer of Venus.

MICROWAVESMagellan Beginning in 1990 and continuing until 1993, the Magellan spacecraft mapped the surface of Venus using radar ranging. 11

INFRARED RAYSInfrared= below redShorter wavelength and higher frequency than microwaves.You can feel the longest ones as warmth on your skinHeat lamps give off infrared waves.Warm objects give off more heat energy than cool objects.Thermograma picture that shows regions of different temperatures in the body. Temperatures are calculated by the amount of infrared radiation given off. Therefore people give off infrared rays.

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Digital Infrared Thermal Imaging Using UV radiation13

VISIBLE LIGHTShorter wavelength and higher frequency than infrared rays.Electromagnetic waves we can see.Longest wavelength= red lightShortest wavelength= violet (purple) lightWhen light enters a new medium it bends (refracts). Each wavelength bends a different amount allowing white light to separate into its various colors ROYGBIV.

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The visible light spectrum ranges from short-wavelength violet to long-wavelength red. Photons of light from violet end of the spectrum have the highest energies and the highest frequencies, while red photons have lower energies and lower frequencies.

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ULTRAVIOLET RAYSShorter wavelength and higher frequency than visible lightCarry more energy than visible lightUsed to kill bacteria. (Sterilization of equipment)Causes your skin to produce vitamin D (good for teeth and bones)

16Used to treat jaundice ( in some new born babies.)Too much can cause skin cancer. Use sun block to protect against (UV rays)

We see this flower in normal light, but the main pollinators of this flower, like bees, see the flower in UV light.ULTRAVIOLET RAYS18

X- RAYSShorter wavelength and higher frequency than UV-raysCarry a great amount of energyCan penetrate most matter.Bones and teeth absorb x-rays. (The light part of an x-ray image indicates a place where the x-ray was absorbed)Too much exposure can cause cancer (lead vest at dentist protects organs from unnecessary exposure)Used by engineers to check for tiny cracks in structures.The rays pass through the cracks and the cracks appear dark on film.19

X- RAYS20

GAMMA RAYSShorter wavelength and higher frequency than X-raysCarry the greatest amount of energy and penetrate the most.Used in radiation treatment to kill cancer cells.Can be very harmful if not used correctly.21

GAMMA RAYS22

A. All electromagnetic waves travel at the same speed. (300,000,000 meters/second in a vacuum.B. They all have different wavelength and different frequencies.Long wavelength-lowest frequencyShort wavelength highest frequencyThe higher the frequency the higher the energy.SUMMARY23