Wave NotesWaves

General and Electromagnetic

• Waves carry energy & information

• The information carried could be:–Sound–Color–Pictures

• Radio waves – tv• Microwave – cell

phones• WAVES DO NOT

CARRY THE MEDIUM!!! (Ex: water)

Transverse Waves• Energy moves left to

right• Wave moves up & down

–Ex: water waves–A Rope that is moved up

and down–Light

• Wave and energy move perpendicular to each other.

Longitudinal Waves• Wave and

energy are in same direction–Ex: Slinky–The

compression will move along the slinky forward and then back.

–Sound

Also called Compressional Waves

–Crests: high point of the wave

–Troughs: low point of the wave

Parts Of A Transverse Wave

Wavelength ( ):–The length of one complete cycle of a wave.

–From crest to crest or trough to trough.

AmplitudeHow big or little the wave is. Tells you how much energy the wave has.The bigger the wave, the more energy it has.

Parts of a Longitudinal Wave• Compression-The condensed portion

• Rarefaction-The separated part of the wave.

• Wavelength-distance from compression to compression

Frequency• How many waves pass in 1 sec.• A wave carries its frequency to

every area that it reaches• Measured in hertz (Hz)

Speed of a Wave• How fast the

wave can transfer energy.

• v = f x • v = speed

(velocity) Units=m/s

• f = frequency Units=Hz

• = wavelength Units=m

• TRANSVERSE WAVES!!!!• All travel at the same speed• The difference is in the frequency and the wavelength.

If one goes up, the other goes down.

Parts of the EM Spectrum

• Radio Waves-Longest wavelength, lowest energy, lowest frequency.

• Used for TV’s, Radios and Cell Phones

Microwaves• A form of radio waves-some books place

them separately and some put them in with radio.

• They are the highest frequency (most energy) of the radio waves.

Infrared (IR)• Heat• Used to find people

in the woods.• Infrared film

detects how hot something is.

• Use to detect cancer

• Beneath red

Visible Light• ROY G. BIV-colors

of visible light.• Sunlight emits UV

along with other rays.

• Gives us Vitamin D• Too much harmful.• Most filtered by

ozone.• Red is longest

ultraviolet• Main source is sunlight• Helps your body produce vitamin D• Overexposure = burns and skin cancer• Sunscreen helps to block• Beyond violet

X-rays and Gamma Rays

• X-rays-See bones.• High Energy• Use lead to block!• Gamma rays-

highest energy• Use to treat cancer• Generated by

radioactive atoms

Wave Interactions• Interaction -Wave run into

other object or another wave• Interaction can increase or

decrease wave energy• Interaction can change the

properties of the wave• Interaction can change the

direction

Reflection• A wave bouncing off

of a surface– Mirror– Wave hitting a wall

• Incident wave – moving to surface

• Reflected wave – moving away from surface

Refraction• Bending of wave as it changes

speed• Speed changes from on medium

to another–Air to water–Water to oil

Diffraction• Bending of a wave when it comes

into contact with the edge of another object

• Light bending around a door

Interference• The effect of 2 or more waves

interacting• Can be constructive or destructive

Constructive Interference

• Wave crest come together at the same location

• Waves join together to make a larger wave

Destructive Interference• The crest of one wave

meets the trough of another wave

• Crest and trough subtract from each other to make a smaller wave

• Sometimes the interference cancels both waves

Doppler Effect• Sound• Change in frequency

and pitch of a sound that is caused by either the movement of the source or the listener

• Ambulance• Race car