Chapter 14Sound 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 WavesThere 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?

WavelengthThe 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 GasesSound moves very quickly through a solid.

Sound moves a little slower through water.

Sound moves slowest through gases.

EchoesAn 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.

PitchIt 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/search?Ntt=frequency+and+qavelength

Lesson 3What 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 lightThe 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.

ShadowsA shadow is created when an

object blocks light.

Electromagnetic SpectrumScientists 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 all carry energy.

It is harmful for humans to absorb the high-energy

waves.

Lesson 4How do light and matter interact?

What is matter?Matter is any object that has mass.

Light and Matter TogetherLight waves travel in a straight

line until an object gets it the way. Then 3 different things can

happen:1. Light waves can reflect off the object2. Light waves can pass through the

object3. Light waves can be absorbed by the

object.

ReflectionReflection occurs when light rays bounce, or reflect, from a surface back to our eyes.

AbsorptionAbsorption 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 ThroughMaterials can be grouped

into 3 categories based off of how much light they let through.• Transparent• Translucent• Opaque

TransparentIf 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.

OpaqueIf a material is opaque, that means NO light rays pass

through it.

Light TravelingLight travels differently through

different mediums.

Light travels slowly through gases, it travels slower

through a liquid, and it travels slowest through a solid.

RefractionWhen light travels from one

medium to another, it can bend or “refract”.

The change in speed is what causes the bending.

LensLenses 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 LensesThis type of lens is thicker in the middle than at the edges. It is

shaped somewhat like a football.

Convex Lens ContinuedWhen 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 LensThis types of lens is thinner in

the middle than at the edges. It is

shaped an hour glass.

Concave Lens ContinuedWhen 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.