what is a wave? chapter 12 section 3 glencoe pages 452-458
TRANSCRIPT
What is a Wave?
Chapter 12 Section 3Glencoe Pages 452-458
I. Types of waves
A. What is a wave?
1. Wave – a disturbance that carries energy
through matter or space
the matter moves very little
the energy moves
Most waves travel through a medium
2. Most waves travel through a medium
a. medium – matter through which a
wave travels
ripples in a pond move through water
sound waves travel through the air
Mechanical waves
b. Mechanical waves – waves that require a
medium to travel
almost all waves are of this type
Electromagnetic waves
c. Electromagnetic waves – waves caused by electric and magnetic fields that do not require a medium
Electromagnetic spectrum of waves,
consisting of: Radio waves, Microwaves, Infrared waves, Visible
light, Ultraviolet waves, X-rays, and Gamma rays
Electromagnetic waves
Electromagnetic waves
Electromagnetic waves
Wave Energy3. Waves transfer energy energy is the ability to do work waves have energy therefore waves can do work
example: water waves on a boat
Wave Energy
Example: light waves on the eyes
Wave Energy
Example: sound waves on your eardrum
*Bigger waves carry more energy
Wave Energy
4. Energy may spread out as a wave travels
- sound waves, ripples in a pond move out
in circular patterns called wave fronts,
and get bigger farther from the source
and the energy spreads out along the
entire wave front
B. Vibrations and waves1. Most waves are created
by a vibrating
object
2. Vibrations involve a
transformation of
energy, generally
between potential
and kinetic
C. Transverse and longitudinal waves
1. Particles in a medium can vibrate up
and down or back and forth
2. Waves are classified by the direction of
particle movement
Transverse and longitudinal waves
3. Transverse waves – waves causing the particles of the medium to vibrate perpendicular to the direction the wave is traveling.Ex. Crowd doing the wave, light waves
Link to waves
Transverse and longitudinal waves
4. Longitudinal waves – waves causing the medium particles to move parallel to the wave’s direction of travel
squeezing together (compression) spreading apart (rarefactions)
ex. Sound waves
Surface waves
5. Surface waves – occur at boundaries between different mediums
air and water
- these waves move both in a transverse and a longitudinal way.
Wave Properties and Forms
Chapter 12 Section 3: Holt Physics
Continued
II. Two Basic Wave Forms
A. Pulse wave – a single non-periodic wave
A single traveling wave
Example:
II. Two Basic Wave Forms
B. Periodic wave – wave whose source is
some form of periodic motion
Bouncing spring, wave machine
Example:
III. Wave properties A. Transverse waves look like a sine curve (looks
like an “S” on its side)
- example drawing – all parts labeled
I. Wave properties
Transverse wave picture
- sine waves with the shape of a sine curve- Waves whose particles move
perpendicular to the direction of wave
motion
B. Parts of a transverse wave1. Crest – highest point on a transverse wave
2. Trough – lowest point on a transverse wave
3. Amplitude – greatest distance a particle is displaced from its normal resting position
B. Parts of a transverse wave4. Wavelength – distance between 2
successive identical points on a wave
symbol = (lambda) measured in meters
C. Longitudinal waves1. No crests or troughs2. Compressions and rarefactions (stretched)- example drawing of longitudinal wave (click on
picture)
C. Longitudinal waves Wave whose particles move parallel to the direction
of wave motion
Compressions – areas where the medium is squeezed together closer than at equilibrium
Rarefactions – areas where the medium is stretched or expanded farther apart than at equilibrium
One wavelength is from compression to compression or rarefaction to rarefaction
Longitudinal Waves
Longitudinal waves examples
Example #1
Example #2
IV. Period, Frequency, and Wavespeed The source of the vibration determines the frequency
Frequency (f)– number of wavelengths that pass a point in 1 second measured in hertz (Hz) named after Heinrich Hertz (1888) 1 Hz = 1 wavelength (vibration) per second
can hear 20 Hz (low) 20,000 Hz (high)
Frequency of a vibrating object = frequency of a wave Frequency (f) = # of vibrations per second # vibrations / time
IV. Period, Frequency, and Wavespeed Wavespeed = frequency x wavelength
V (m/s) = f (hz) x (m)
The wavespeed of a mechanical wave is constant for a given medium
Period (T) – time required for one full wavelength to pass a certain point (measured in seconds)