Waves General and Electromagnetic Unit 9 Notes Waves 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.

Also called Compressional Waves Longitudinal Waves Also called Compressional Waves Wave and energy are in same direction Ex: Slinky The compression will move along the slinky forward and then back. Sound

Parts Of A Transverse Wave Crests: high point of the wave Troughs: low point of the wave

Wavelength ( ): The length of one complete cycle of a wave. From crest to crest or trough to trough.

Amplitude How 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 Images of structure inside the human body X-rays-See bones. Airport screening devices Used to treat cancer

Gamma Rays High Energy Use thick lead to block! Gamma rays-highest energy, shortest wavelength, highest frequency Generated by radioactive atoms Used to treat cancer

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 Law of Reflection – wave bounces off the surface at the same angle that it entered the surface

Light reflection Mirror Radar –weather and flying object

Reflection of sound ECHO Concert halls want to minimize echo Good acoustics Bats use echolocation to find food at night

Sonar Reflection of sound from the bottom of the ocean floor to detect depth or objects Whales and dolphins use this also

Ultrasound Reflecting sound waves in the body Used in medicine to monitor patients Pregnancy Heart disease Cancer

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

Polorization Unpolarized light contains light waves moving in all directions We can use filters to stop waves traveling in certain directions

Polarizers Used in Sunglasses Photography Windsheilds Digital watches Laptop screens