Chapter 14
Sound and Light Energy
Lesson 1:
What is sound energy?
Sound energy is a form of energy that
travels in waves.
Sound can travel through solids, liquids, and
gases.
How is the sound made?
Sound is actually created by objects
vibrating.
A vibration is a kind of wiggle; a quick
back-and-forth movement.
How the vibration works!
Think about a guitar:
When you pluck a string, the string vibrates.
When it vibrates energy is passed into the air
causing the air to vibrate as well.
The vibrations travel through the air as sound
waves. A sound wave is a disturbance that moves
energy through matter.
Sound Waves
There are 2 types of sound waves:
1. Transverse (sound travels up and
down)
2. Longitudinal (sound that travels left to
right)
Frequency
The number of waves
that pass a
point in a certain
length of time.
How frequently does
the sound wave
happen?
Wavelength
The distance between one point on a wave
and another point on a different wave.
How does sound travel?
Sound waves compress the particles in
whatever kind of matter it is traveling in.
It can travel in solids, liquids, and gases.
Sound travels at different speeds through
different kinds of matter.
Why do sounds travel at different speeds?
There are 2 main causes that affect how fast the
sound travels through the medium.
1. How much do the particles move in response
to the vibration and how easily they move
back to their original position?
2. How strongly are the particles attached or
attracted to one another?
Solids, Liquids, and Gases
Sound moves very quickly through a solid.
Sound moves a little slower through water.
Sound moves slowest through gases.
Echoes
An echo is a reflected sound. When a
sound is traveling it sometimes bumps into
objects.
Think about being in a cave- if you yelled
your name in a cave, you would hear
your name echo because of the walls that
surround you.
Lesson 2
How is sound made?
Frequency, Wavelength,
and Pitch
Frequency
Frequency is how
often the
sound wave
occurs in a
given amount
of time.
Wavelength
Wavelength is
the length
from one top
of a sound
wave to the
next top of
sound wave.
Pitch
It is what makes a sound seem
low or high. It depends on a sound
frequency.
If an object vibrates slowly, the pitch is
low and the frequency is low.
If an object vibrates quickly, the pitch is
high and the frequency is high.
Video
http://app.discoveryeducation.com/se
arch?Ntt=frequency+and+qavelength
Lesson 3
What is light
energy?
What is light?
Light is a form of energy, that travels in
waves.
How does light travel?
Light travels in waves known as
transverse waves.
Light travels in a straight line
called a ray. A ray fans outward
from the source of light.
Sources of light
The most important source of light is the Sun.
Some animals give off light called “bioluminescence”
which is created because of a chemical reaction in
the animal’s body.
Shadows
A shadow is created when an
object blocks light.
Electromagnetic Spectrum
Scientists refer to all forms of
light energy as electromagnetic
radiation.
The human eye can only see the wavelengths and the
frequencies in the visible spectrum.
Electromagnetic Spectrum Continued
As you move from left to right on the spectrum,
wavelength decreases and frequency increases.
So, red light has the longest wavelength and lowest
frequency, and violet light has the shortest wavelength
and highest frequency.
Light Waves We Can’t See
Ultraviolet waves, x-rays, and
gamma rays are high-energy wave.
The are invisible to the human
eye because their waves are
too short.
Did You Know This?
All electromagnetic waves
travel at the same speed
through empty space and they
are carry energy.
It is harmful for humans to absorb the high-energy
waves.
Lesson 4
How do light and
matter interact?
What is matter?
Matter is any
object that has
mass.
Light and Matter Together
1.
2.
3.
Light waves travel in a straight
line until an object gets it the
way. Then 3 different things can
happen:
Light waves can reflect off the object
Light waves can pass through the object
Light waves can be absorbed by the object.
Reflection
Reflection occurs when light rays bounce, or reflect,
from a surface back to our eyes.
Absorption
Absorption takes place when
an object takes in all the
light waves.
Once this happens the light
turns into heat energy.
What we actually see
When light hits an object, whatever colors the object
reflects is the color we see the object as.
The reason an object looks white, is because it reflects all
colors.
Letting Light Through
Materials can be grouped
into 3 categories based off
of how much light they let
through.
• Transparent
• Translucent
• Opaque
Transparent
If a material is transparent,
that means light rays can
pass through them.
Translucent
If a material is translucent,
that means it lets some light
rays through it.
Opaque
If a material is opaque, that
means NO light rays pass
through it.
Light Traveling
Light travels differently through
different mediums.
Light travels slowly through gases, it travels slower
through a liquid, and it travels slowest through a
solid.
Refraction
When light travels from one
medium to another, it can bend
or “refract”.
The change in speed is what causes the bending.
Lens
Lenses are curved pieces of clear
glass or plastic that refract light
that passes through them.
There are 2 main types of lenses: convex and
concave.
Convex Lenses
This type of lens is thicker in the
middle than at the edges. It is
shaped somewhat like a football.
Convex Lens Continued
When light rays pass through a
convex lens the light rays bend
in toward the middle of the lens.
A convex lens can magnify an object, making them look
larger.
An example of a convex lens would be a magnifying glass
or a microscope.
Concave Lens
This types of lens is thinner in the
middle than at the edges. It is
shaped an hour glass.
Concave Lens Continued
When light passes through a
concave lens, the light rays bend
out toward the thicker edges of
the lens.
When looking through concave lens, the light rays spread apart,
so the object seems smaller than it is.
Many telescopes have this kind of lens.