Warm Up

1. What is energy?2. What is kinetic energy? How do you

calculate it?3. What is potential energy?4. What is a transverse wave? Draw and

label. 5. What is a longitudinal wave? Draw and

label.

I. Electromagnetic Waves

Waves… a review

Most waves are either longitudinal or transverse.

Sound waves are longitudinal.But *all electromagnetic waves are

transverse…

?

?

1. When an electric field changes, so does the magnetic field. When one field vibrates—so does the other.

2. RESULT- An electromagnetic

wave.

Click here Animation: Interaction of vibrating charges

A. Electromagnetic waves1. Produced by the movement of electrically

charged particles. They are transverse waves

2. Can travel in a “vacuum” (they do NOT need a medium)

3. Travel at the speed of

light: 300,000,000 meters/second (Takes light 8 minutes to move from

the sun to earth {150 million miles}

at this speed.)

(Also known as EM waves)

Waves of the Electromagnetic SpectrumElectromagnetic Spectrum—name for the

range of electromagnetic waves when placed in order of increasing frequency

Click here (Animation—Size of EMwaves)

RADIO WAVES

MICROWAVES

INFRARED RAYS

VISIBLE LIGHT

ULTRAVIOLET RAYS

X-RAYS

GAMMA RAYS

Wave-particle Duality

Light can behave like a wave or like a particle

A “particle” of light is called a photon

Radio wavesHave the longest wavelengths and

lowest frequencies of all the electromagnetic waves.

Uses:TV broadcastingAM and FM broadcast radio ( each channel is

a different frequency)Cell phone communication

MicrowavesMicrowaves—have 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.

How does a microwave oven work?

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.)

Infrared RadiationWavelengths in between microwaves and

visible light Infrared means Before RedUses:

Night vision gogglesRemote controlsHeat-seeking missiles

Visible light

Only type of EM wave able to be detected by the human eye

Violet is the highest frequency lightRed light is the lowest frequency light

Ultraviolet

Shorter wavelengths than visible lightUses:

Black lightsSterilizing medical equipmentWater disinfectionSecurity images on money

Ultraviolet (cont.)

UVA UVB and UVC

Energy Highest of UV waves

Lower than UVA

Health risks

Extremely low risk for DNA damage Can destroy Vitamin A in skin

Can cause DNA damage, leading to skin cancer Responsible for sunburn

X-rays

Tiny wavelength, high

energy wavesUses:

Medical imagingAirport securityInspecting industrial welds

Gamma Rays

Smallest wavelengths, highest energy EM waves

UsesFood irradiationCancer treatmentTreating wood flooring

Using the EM waves to view the Sun

Animation—View a Galaxy at different wavelengths

Brief SUMMARYA. 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.