Waves Unit Test Review

Waves, Sound, Light, and Color

Winter 2014

Define a wave.

• Caused by disturbance

• Carries energy (and SOMETIMES particles)

List 4 ways we categorize waves.

• Mechanical: require a medium (matter) to travel; ALL longitudinal waves are mechanical; SOME transverse waves are mechanical.

• Transverse: move particles perpendicular to direction; not all require a medium; can carry energy AND particles.

• Longitudinal: particles vibrate back and forth to direction; all require a medium

• Electromagnetic: ALL transverse waves; ONLY carry energy (NOT particles)

What do ALL waves carry? What can waves carry in a medium?

• All waves carry ENERGY!

• Waves traveling in a medium can carry energy AND particles!

Differentiate between the 2 types of interference.

• Constructive Interference: waves combine to form larger waves

• Destructive Interference: waves combine to cancel each other out

Draw and Label ALL the parts of a transverse wave.

State 3 characteristics of a transverse wave.

• Moves particles perpendicular to direction of the wave

• Many do NOT require a medium

• ALL electromagnetic waves are transverse

What is frequency? How is it measured?

• Frequency is the number of waves per second

• Measured in Hertz (Hz)

• High frequency = high energy

• Low frequency = low energy

What is amplitude? How does intensity relate to amplutude?

• Amplitude is the distance the wave moves from the rest position (equilibrium)

• Frequently referred to as “wave height”

• More amplitude = more energy (intensity)

• Intensity = energy!

Draw and Label ALL the parts of a longitudinal wave.

State 3 characteristics of a longitudinal wave.

• Particles vibrate back and forth parallel to direction of wave

• ALL require a medium!

• ALL sound waves are longitudinal!

How does the speed of sound vary in traveling through solids, liquids, and gases?

• Speed travels BEST (fastest) through solids (the particles are already touching!)

• Speed travels GOOD (medium) through liquids (particles are still touching, but spread apart to slip by each other)

• Speed travels OK (slowest) through gases (particles are spread out)

How does temperature play a part in how longitudinal waves travel?

• Sound travels FASTER in WARMER temperatures.

• Sound travels SLOWER in COLDER temperatures.

Draw and example of reflection, refraction, diffraction, and absorption.

Reflection Refraction

Diffraction Absorption

How does sound travel?

• In a longitudinal waves that require a medium!

What do frequency and pitch have in common?

• Frequency determines pitch.

What does high and low frequency indicate in relation to pitch?

• High frequency = high pitch (high energy/intensity) and short wavelength

• Low frequency = low pitch (low energy/intensity)and longer wavelength

How are amplitude and loudness related?

• Amplitude determines loudness.

• High amplitude = increases loudness

• Low amplitude = decreased loudness

What is the Doppler Effect? Give an example.

• Doppler Effect is the apparent change in frequency as a sound source moves toward a listener. Also called Red shift/Blue Shift!

• Example: emergency sirens

Doppler Effect

Red Shift/Blue Shift

What is loudness? What unit do we use to measure loudness?

• Loudness is the amplitude (height) of a sound wave.

• Loudness is measured in decibels (db)

What is an echo?

• An echo is a reflected sound wave.

What is resonance?

• Resonance occurs when objects near one another vibrate at the same frequency.

http://www.youtube.com/watch?v=17tqXgvCN0E

Click on the link to watch resonance in action!

At what average speed can sound travel through air?

• Sound travels @ 330 m/s through air.

Does sound travel faster through warmer or cooler temperatures?

• Sound travels faster through warmer air.

• Sound refracts DOWN in warmer air

• Sound refracts UP in cooler air

Explain how the electromagnetic spectrum is organized. Which waves have the longest wavelength? Which waves have the

shortest wavelength?

• The EM Spectrum consists of ALL electromagnetic waves organized by WAVELENGTH and FREQUENCY.

• From LONGEST to SHORTEST (lowest energy to highest energy): radio, microwave, infrared, visible light (ROY G BIV), ultraviolet (UV), x-ray, and gamma

• Longest wavelength = RADIO

• Shortest wavelength = GAMMA

EM Spectrum!

How does frequency play a role in the organization of the EM spectrum?

• Higher the frequency, higher the energy, shorter wavelength

• Lower the frequency, lower the energy, longer wavelength

What do electromagnetic waves carry?

•ENERGY ONLY!!!

What categories of waves describe light?

• Transverse and Electromagnetic – NO MEDIUM REQUIRED!!

What is the Law of Reflection? Draw an example.

• Law of Reflection states that light reflects off at the same angle that it strikes an object.

How fast can light travel?

• The speed of light is @ 300,000,000 m/s.

• Takes @ 8 minutes for light from the sun to reach the Earth.

Why can we see objects?

• We see objects because they either produce their own light OR they reflect light!

What are the 3 primary colors of light? When combined in equal parts, what do they create?

• 3 primary colors of light: RED, BLUE, GREEN

• When mixed in EQUAL portions, they create WHITE light!

What are the 3 primary colors of pigments? When combined in equal parts, what do they create?

• 3 primary PIGMENT colors are: CYAN, MAGENTA, and YELLOW!

• When mixed in EQUAL parts, they create BLACK!

Why can we see the color white?

• ALL colors are reflected!

Why can we see the color black?

• ALL colors are absorbed!

Why is an apple red or a banana yellow? What happens when we shine a different color light on these

objects?

• The color of ANY object is the color that it REFLECTS! ALL other colors are absorbed!

In regard to the visible light spectrum. Which color has the longest wavelength and lowest frequency? Which color has the

shortest wavelength and highest frequency?

RED has the longest wavelength and lowest frequency. Violet/Purple has the shortest wavelength and the highest frequency.

Complete the table. Energy Reflection Refraction Diffraction Absorption Scattering

Sound An echo is a reflected sound wave.

Sound can refract as it changes speeds in media.

Sound diffracts well around a barrier.

Sound can be absorbed.

Sound can be scattered by changing media.

Draw an example

Light Light can be reflected.

Light can be refracted.

Light can be diffracted.

Light can be absorbed.

Light scatters very easily.

Draw an example

Complete the Table Type of Object Reflection Transmission Scattering Absorption

Transparent Minor energy reflection

Most energy transmits

No scattering No absorption

Draw an example

Translucent Minor energy reflection

Minor energy transmission

Most energy scatters

Minor absorption

Draw an example

Opaque Light reflected is what we see

No transmission

No scattering Most energy is absorbed

Draw an example

What is a plane mirror? What kind of reflection does it produce?

• A plane mirror is a flat mirror that produces regular reflection.

Draw and Label an example of a concave and convex mirror.

Convex Mirror

What do concave and convex mirrors do?

Concave mirrors produce an image

that is upside down…like looking at the INSIDE of a

spoon.

Convex mirrors produce an

image that is right side up, yet

a little elongated…like the BACK of a

spoon.

Draw and label an example of a concave and convex lens.

What type of lenses would be used to correct nearsightedness? What type of lenses would be used to

correct farsightedness? Nearsightedness = myopia

• Eyeball is too long. • Can see near. Distance

vision is not great. • Can be corrected with a

combination of convex and concave lenses (glasses or contacts.)

• Additionally, Lasic eye surgery is an option. This procedure uses lasers to reshape the eye to correct blurry distance vision.

Farsightedness – hyperopia

• Eyeball is too short. • Can see far. Close up vision

is not great. • Can only be corrected with

convex lenses (glasses or contacts.)

• Convex lenses clarify a blurry image.