waves and the electromagnetic spectrum 8 th grade

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