Title: WAVES
1WAVES
2What is a wave
- A wave is
- A rhythmic disturbance
- Carries ENERGY but not MATTER
3How can a wave carry energy without carrying
matter?
- Even though the ball is moving from one end of
the line to the other, the people are not moving
with it.
4How do waves move
- Mechanical Waves
- Move through matter
- Energy moves from
- particle to particle
- Examples
- Water waves
- Sound waves
- Earthquake waves
5How do waves move
- Electromagnetic Waves
- Move through empty space
- Do not require matter or particles in order to
move - Example
- Light waves
6Types Of Waves
- Compressional (or Longitudinal) Waves
7Parts Of A Wave
CREST
high point of a transverse wave
AMPLITUDE
half the distance between the crest and trough
WAVELENGTH
TROUGH
distance from top of one crest to the top of the
next OR from one trough to the next
low point of a transverse wave
8Properties of waves
- Amplitude tells how much ENERGY the wave is
carrying - Bright light has higher amplitude than dim
- Loud sounds have higher amplitude than soft
- Large water waves carry more energy than small
ones
9Properties of waves
- Wavelength (?)
- In visible light, ? determines color
?
?
Red has a longer
Violet has a shorter
?
Radio waves and microwaves have longer
?
X-rays and gamma ray have shorter
10Properties of waves
- Frequency the number of ? that pass a given
point in one second, measured in ?/sec hertz - Higher frequency indicates faster vibration of
whatever is generating the wave
11Properties of waves
- Frequency and wavelength are closely related
- Short ? creates a higher frequency
- In sound, this causes a higher pitch
- In light, violet color has a higher frequency
than red - Long ? creates a lower frequency
- In sound, this causes a lower pitch
- In light, red color has a lower frequency than
violet
gt F lt ?
12Properties of waves
WAVE SPEED
- Mechanical Wave
- Travels faster through solids because molecules
are closer together and transmit the sound better
- Electromagnetic Wave
- Travels faster through empty space because there
are no molecules in the way to slow it down
13Wave Behavior
- Reflection a wave strikes a surface and bounces
off
HELLOOOO!!!
HELLOOOO!!!
Reflection are clear when they bounce off a
smooth, even surface. From a rough surface, light
scatters in all directions and the reflection is
distorted.
When sound waves reflect from a surface, it
produces an ECHO.
14Wave Behavior
- Refraction The bending of a wave as it moves
from one medium into another because of a change
in SPEED.
15Wave Behavior
- Diffraction The bending of waves around a
barrier.
LIGHT WAVES Light waves do not diffract as much
as sound waves, so you cant see around corners.
This is because the ? of light is so much
smaller than the width of a door. Diffraction
occurs better when the barrier and ? are similar
in size.
SOUND WAVES You can hear sounds from a room even
when you are not in the room because the sound
waves bend as they pass through the open doorway
WATER WAVES When water waves strike obstacles
such as islands, they bend around the island and
keep moving. If the island was much bigger than
than the wavelength of the water wave, less
diffraction would occur
16Wave Behavior
- Interference The ability of two waves to combine
and form a new wave when they overlap
17INTERFERENCE
- CONSTRUCTIVE Interference
18INTERFERENCE
- CONSTRUCTIVE Interference
19INTERFERENCE
- CONSTRUCTIVE Interference
20INTERFERENCE
21INTERFERENCE
22INTERFERENCE
23Constructive INTERFERENCE
- The crests of two waves A B approach each
other - The two waves form a wave with a greater
amplitude while the crests of both waves overlap
24Constructive INTERFERENCE
- The original waves pass through each other and go
on as they started.
25Destructive INTERFERENCE
- The crest of one wave (A) approaches the trough
of another (B) - If the two waves have equal amplitude, they
momentarily cancel when they meet
26Destructive INTERFERENCE
- The original waves pass through each other and go
on as they started.
27Parts Of A Wave
- Parts of a COMPRESSIONAL WAVE
Compression
Rarefaction
Wavelength
28What did you learn