The Electromagnetic Spectrum

Electromagnetic SpectrumElectromagnetic Spectrum—name for the —name for the range of electromagnetic waves when placed range of electromagnetic waves when placed in order of increasing frequencyin order of increasing frequency

RADIO WAVES

MICROWAVES

INFRARED RAYS

VISIBLE LIGHT

ULTRAVIOLET RAYS

X-RAYS

GAMMA RAYS

The Electromagnetic SpectrumThe Electromagnetic Spectrum

As you go from As you go from left left right right, the , the wavelengths wavelengths get smaller get smaller and the and the frequencies get higherfrequencies get higher. . This is an This is an inverseinverse relationshiprelationship between wave between wave size and frequency. (As one goes up, the size and frequency. (As one goes up, the other goes down.) other goes down.)

Electromagnetic waves travel Electromagnetic waves travel VERY FAST – around 300,000 VERY FAST – around 300,000

kilometers per second (the speed kilometers per second (the speed of light).of light).

At this speed they can go around the world 8 times in one second.

Things to RememberThings to RememberThe higher the frequency, the more energy the The higher the frequency, the more energy the wave has.wave has.

EM waves EM waves do not require media do not require media in which to travel in which to travel or move.or move.

The higher the frequency, the more energy the The higher the frequency, the more energy the wave has.wave has.

Things to RememberThings to Remember

EM waves are considered to be EM waves are considered to be transverse transverse waves waves because they are made of vibrating because they are made of vibrating electric and magnetic fields at right angles electric and magnetic fields at right angles to each other, and to the direction the to each other, and to the direction the waves are traveling.waves are traveling.

Inverse relationship between wave size Inverse relationship between wave size and frequency: as and frequency: as wavelengths get wavelengths get smallersmaller, , frequencies get higherfrequencies get higher. .

Radio wavesRadio waves: Have the longest wavelengths and : Have the longest wavelengths and the lowest frequencies; wavelengths range the lowest frequencies; wavelengths range from 1000s of meters to .001 mfrom 1000s of meters to .001 m

Used in: RADAR, cooking food, satellite Used in: RADAR, cooking food, satellite transmissionstransmissions

Radio WavesRadio Waves

MicrowavesMicrowaves

Microwaves are extremely high frequency Microwaves are extremely high frequency radio waves.radio waves.

Their wavelength is usually a couple of Their wavelength is usually a couple of centimeters.centimeters.

Used for cooking food, mobile phones, and Used for cooking food, mobile phones, and RADARRADARRADARRADAR ( (RaRadio dio DDetection etection aand nd RRanging)anging)

Used to find the speed of an object by sending out Used to find the speed of an object by sending out radio waves and measuring the time it takes them to radio waves and measuring the time it takes them to return.return.

Infrared WavesInfrared Waves

Infrared waves Infrared waves (heat): Have a (heat): Have a shorter wavelength, from .001 m to shorter wavelength, from .001 m to 700 nm, and therefore, a higher 700 nm, and therefore, a higher frequency.frequency.

Used for finding people in the dark Used for finding people in the dark and in TV remote control devicesand in TV remote control devices

ROY G. BVROY G. BV

redred

orangeorange

yellowyellow

greengreen

blueblue

violetviolet

Visible LightVisible Light

Remembering the OrderRemembering the Order

Visible lightVisible light: Wavelengths range from 700 nm (red : Wavelengths range from 700 nm (red light) to 30 nm (violet light) with frequencies higher light) to 30 nm (violet light) with frequencies higher than infrared waves.than infrared waves.

These are the waves in the These are the waves in the EM spectrum that humansEM spectrum that humanscan see.can see.

Visible light waves are a very Visible light waves are a very small part of the EM spectrum! small part of the EM spectrum!

Ultraviolet LightUltraviolet Light: Wavelengths: Wavelengths range from 400 nm to 10 nm; the frequency (and therefore the energy) is high enough with UV rays to penetrate living cells and cause them damage.

Although we cannot see UV light, bees, bats, butterflies, some small rodents and birds can.

UV on our skin produces vitamin D in our bodies. Too much UV can lead to sunburn and skin cancer. UV rays are easily blocked by clothing. https://www.youtube.com/watch?v=o9BqrSAHbTc

Used for sterilization because they kill bacteria.

X-RaysX-Rays: Wavelengths from 10 nm to .001 nm. : Wavelengths from 10 nm to .001 nm. These rays have enough energy to penetrate These rays have enough energy to penetrate deep into tissues and cause damage to cells; deep into tissues and cause damage to cells; are stopped by dense materials, such as bone.are stopped by dense materials, such as bone.

Used to look at solid structures, such as bones and Used to look at solid structures, such as bones and bridges (for cracks), and for treatment of cancer.bridges (for cracks), and for treatment of cancer.

Gamma RaysGamma Rays: Carry the most energy and have : Carry the most energy and have the shortest wavelengths, less than one the shortest wavelengths, less than one trillionth of a meter (10trillionth of a meter (10-12-12). ).

Gamma rays have enough energy to go through Gamma rays have enough energy to go through most materials easily; you would need a 3-4 ft thick most materials easily; you would need a 3-4 ft thick concrete wall to stop them!concrete wall to stop them!

Gamma rays are released Gamma rays are released by nuclear reactions in by nuclear reactions in nuclear power plants, by nuclear power plants, by nuclear bombs, and by nuclear bombs, and by naturally occurring naturally occurring elements on Earth.elements on Earth.

Sometimes used in the Sometimes used in the treatment of cancers.treatment of cancers.

Gamma RaysGamma Rays

This picture is a This picture is a “scintigram” “scintigram” It shows an asthmatic It shows an asthmatic person’s lungs.person’s lungs.

The patient was given a slightly radioactive gas to The patient was given a slightly radioactive gas to breath, and the picture was taken using a gamma breath, and the picture was taken using a gamma camera to detect the radiation. camera to detect the radiation.

The colors show the air flow in the lungs.The colors show the air flow in the lungs.

Brief SUMMARYBrief SUMMARYA.A. All electromagnetic wavesAll electromagnetic waves travel at the travel at the same speed. (300,000,000 meters/second) same speed. (300,000,000 meters/second) in a vacuum.in a vacuum.B. They all have different B. They all have different wavelengthswavelengths and and different different frequencies.frequencies.– Long wavelength-Long wavelength-lowest frequencylowest frequency– Short wavelengthShort wavelength highest frequency highest frequency– The higher the frequency the The higher the frequency the higher the energy.higher the energy.