Waves and the Electromagnetic Spectrum8th grade
What is a wave? A rhythmic disturbance that carries energy but not
matter It is able to make matter move
This is called a mechanical wave- it uses matter to trasfer energy
Types of Mechanical waves Transverse waves- moves at a right angle to the
direction of the wave Like up and down Side to side
They create peaks and troughs Like a rope Radio wave
Compressional waves Moves forward and backward in the direction of the
wave Like an accordion
Sound waves are compression waves Every sound is made by a vibration
How to measure waves Amplitude- the amount of energy a
wave has
The distance of the crest or the trough of a wave to the midline. This is the amplitude of a wave
Measure in decibels- how loud it is.
Wavelength describes frequency, or how fast a wave is. Frequency= number of wavelengths per second
Measured in hertz It also tells us where a wave will fall on the
electromagnetic spectrum A view of all the wavelengths from
very fast gamma rays To very slow radio waves
The measure from one crest to another.
Wavelength does not have to be equal to amplitude, they are separate
Color and pitch are based on wavelength Faster wavelength= faster vibration and higher pitch Blue light has a faster frequency than red light
This is what it used for photosynthesis, more energy
Sound Waves travel better through dense mediums like solids.
Electromagnetic waves, like light travel best in open space This is why we get light from the sun so fast But it changes direction as it hits the atmosphere
Reflection and refraction reflection is when a wave bounces off an
object and changes direction Echo and mirrors
Refraction is when the wave slows down and changes its angle as it passes from one medium to the other. A glass with water in it
refraction
Doppler effect- sound waves get compressed causing a high pitch as the object gets closer to you. as the object moves past the sound waves get longer and the tone gets lower. Like a siren
Blue-red shift- as light moves away from you it get red, because red has a longer wave length As light come toward you it is blue, blue
has a shorter wave length
Use Doppler effect to Check speed for police radar Check position of satellites Get information over stars and other
planets Are they moving away or towards us, we
can tell by the wavelength we receive
Lenses and mirrors Concave and convex
Draw and describe the differences
Transparent, translucent, opaque
Diffraction
Bending of waves around a barrier Like a rainbow Like water waves moving around an
objectThey separate and move around the
object Remember, a wave is energy and it will
keep moving untie all energy is released
Wave Interference When 2 waves combine to form 1 wave
Constructive interference- amplitude increases
Destructive interference- amplitude decreases Occurs when trough and crest meet Used in noise canceling headphones