1. Waves and the Electromagnetic Spectrum
8th grade

2. 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

4. 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

5. 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

6. 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.

8. 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.

10. 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

11. 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

13. 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

14. refraction

15. 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

17. 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

18. Lenses and mirrors Concave and convex Transparent, translucent, opaque
Draw and describe the differences
Transparent, translucent, opaque

19. Diffraction Bending of waves around a barrier Like a rainbow
Like water waves moving around an object
They separate and move around the object
Remember, a wave is energy and it will keep moving untie all energy is released

21. Wave Interference When 2 waves combine to form 1 wave
Constructive interference- amplitude increases

22. Destructive interference- amplitude decreases
Occurs when trough and crest meet
Used in noise canceling headphones