8Th Physical Science WAVES, LIGHT, & SOUND STUDY GUIDE - Answer Sheet

8th Physical Science WAVES, LIGHT, & SOUND STUDY GUIDE - Answer Sheet

1)

The picture lists light waves from left to right in order of highest to lowest energy. Which region of the electromagnetic spectrum has the longest wavelength?

A) / UV
B) / Gamma Rays
C) / Radio Waves
D) / Visible Light

Explanation:
Radio waveshave the lowest energy, lowest frequency and, due to the inverse relationship, the longest wavelengths.

2)Ultraviolet radiation is dangerous because it has a high enough energy to damage skin cells. UV radiation is called ultraviolet because it has a frequency which is higher than violet radiation (purple light). Therefore, it has a wavelength which is ______than violet radiation.

A) / bigger
B) / smaller
C) / the same size
D) / the square root of

Explanation:
Frequency and wavelength are inversely proportional. This means that as one goes up, the other goes down. Since the frequency of UV light is larger, its wavelength must besmaller.

3)An echo is an example of sound wave

A) / diffraction.
B) / interference.
C) / reflection.
D) / refraction.

Explanation:
An echo is the bouncing back of a sound wave off of a surface, this isreflection.

4)You attend a football game one day and notice a long time difference between when the other side of the stadium stands up to cheer and when you hear them. This time difference would be lessened if

A) / it were warmer.
B) / it were less humid.
C) / it were located at a higher altitude.
D) / the fans on the opposite side shouted louder.

Explanation:
Ifit were a warmertemperature, the air molecules would be moving faster. If particles are moving faster, they can transmit sound faster.

5)

Which form of radiation from the electromagnetic spectrum is MOST LIKELY to cause mutations in growing tissues, and should be MOST avoided by pregnant women?

A) / microwaves
B) / gamma rays
C) / radio waves
D) / ultraviolet rays

Explanation:
Gamma rays are the highest in energy, and therefore cause the most damage. Cancers, mutations and cell damage can easily occur with exposure to large amounts of gamma radiation.

6)The speed of sound is greater through a solid than through a gas because the molecules in a solid are

A) / still.
B) / vibrating.
C) / farther apart.
D) / closer together.

Explanation:
Sound is vibrating molecules and the closer the molecules are, the more quickly they bump into one another. In a solid, molecules arecloser together.

7)Longitudinal waves compress the medium they travel though. One example of a longitudinal wave is a

A) / sound wave.
B) / ocean wave.
C) / infrared wave.
D) / ultraviolet wave.

Explanation:
Although both ocean waves and sound waves need a medium, only asound wavecompresses the medium. Infrared and ultraviolet waves are electromagnetic waves or transverse waves.

8)

______lenses refract light rays in toward a central point. When this lens is held close to your eye, the image is magnified and right side up.

A) / Concave
B) / Convex
C) / Prismatic
D) / Refractive

Explanation:
Convexlenses refract light rays in toward a central point. We often use these lenses to magnify objects. But if the lens is held far from your eye, the image seem through a convex lens will be upside down.

9)

The distance shown in the diagram is known as the

A) / amplitude.
B) / crest.
C) / trough.
D) / wavelength.

Explanation:
The distance shown here changes as a wave gains or loses energy and is known as itsamplitude. It is the distance from base line to crest or base line to trough.

10)

What factor is responsible for altering the speed of an electromagnetic wave?

A) / amplitude
B) / wavelength
C) / type of medium
D) / frequency of the wave

Explanation:
All electromagnetic waves travel at the same speed regardless of frequency, wavelength, or amplitude. The factor that influences the speed of an electromagnetic wave is thetype of mediumthe wave is passing through.

11)It seems like everyone has a cell phone these days. Sounds, images, and the written word can all instantly be sent using this technology. How do cell phones send information from one person to another?

A) / Sound waves are sent through the air.
B) / Sound waves are sent through overhead cables.
C) / The signals are sent through underground cables.
D) / The signals are sent through communication satellites.

Explanation:
The signals are sent through communication satellites. Cellular phones work on wireless technology.

12)Maria and Sarah made a set of paper cup telephones. First the girls punched a hole in the bottom of each cup. Then they connected the cups with a very long piece of string, knotted in the bottom of each cup. Maria went down the hall to her bedroom while Sarah stayed in the kitchen. When Maria put the cup to her ear she could hear Sarah talking to her because.

A) / they were not that far from each other.
B) / sound waves traveled through the string to Maria’s cup.
C) / sound waves traveled through the air from room to room.
D) / sound waves bounced off of the walls to reach Maria in the bedroom.

Explanation:
Sound waves are vibrations that form compression waves. They travel fastest through solids, like the string. Maria could hear Sarah talk becausesound waves traveled through the string to Maria’s cupand then to Maria’s ear.

13)

As the band passed by, the beating drums and trumpets made Billy feel like his body was beating with the music. He could hear the music and he could feel it!
How would a scientist explain this to Billy?

A) / Sound waves cannot travel through the air
B) / Sound waves transmit energy through all forms of matter.
C) / The marching causes the ground to move which Billy feels
D) / Sound waves are transmitted faster through gases than through solids.

Explanation:
Sound waves transmit energy through all forms of matter.Sound waves do cause the air to vibrate, but they may also cause the ground as well as Billy to vibrate because sound waves can be transmitted through solids and liquids, not just air or gases.

14)Which phenomenon causes an object to appear bent from above the surface of one medium to below the surface of another medium?

A) / diffraction
B) / dispersion
C) / reflection
D) / refraction

Explanation:
Refractionis the phenomenon that causes an object to appear bent from above the surface of one medium to below the surface of another medium.

15)What happens when light strikes a transparent object?

A) / All the light passes through the object
B) / None of the light passes through the object
C) / All of the light is reflected then reabsorbed
D) / Some of the light is scattered or absorbed and some passes through.

Explanation:
All the light passes through the object.Glass, like in a windshield, is a transparent object.

16)

Sara is using a magnifying glass to closely examine her stamp collection. Why type oflensis found in a magnifying glass?

A) / bifocal
B) / concave
C) / convex
D) / prismatic

Explanation:
Magnifiers contain oneconvexlens. A convex lens has a thick middle and thin edges.

17)Reflection is the bouncing of light rays off of a surface. Which situation is NOT an example of reflection?

A) / looking at yourself in a mirror
B) / focusing light through a camera lens
C) / seeing an image of yourself in a still lake
D) / looking at your teacher at the front of the class

Explanation:
A and C are cases where light is bounced and reflected off a surface. What seems a little strange is that whenever you see anyone or anything, the reason you see them is that light (from the sun, or from electric lights) actually bounces off of them to get to your eye so you can see them. This leavesfocusing light through a camera lenswhich is actually an example of refraction.

18)

A convex lens bulges outward in its center. and it refracts light rays towards its center. Which represents a convex lens?

A) / A
B) / B
C) / A and B
D) / neither A nor B

Explanation:
A convex lens has a shape likeA. The lens bulges outward in its center, like reading glasses.

19)CD's and DVD's both are applications of light. Light is used to read the information on the disc. Which property of light is used in this technology?

A) / Diffraction
B) / Interference
C) / Reflection
D) / Refraction

Explanation:
Reflectionis used to read the information on the discs.

20)Eyeglasses bend light help the image form properly on the retina. The bending of light as it passes from one medium to another is called

A) / diffraction
B) / interference
C) / reflection
D) / refraction

Explanation:
The bending of light when it changes speed as it passes from one medium to another is calledrefraction.

21)

What statement explains the changes from wave A to wave B?

A) / The energy and amplitude increase.
B) / The energy and amplitude decrease.
C) / The energy decreases as the amplitude increases.
D) / The energy increases as the amplitude decreases.

Explanation:
What statement explains the changes from wave A to wave B?The energy and amplitude increase.

22)

Sound travels in waves. Sound waves cannot travel through

A) / air.
B) / solids.
C) / space.
D) / water.

Explanation:
Sound waves can only travel through a medium. Sound waves cannot travel throughspace.

23)

Which choice BEST represents the sound waves from a soft low-pitched train rumble that suddenly shifts to a loud, high-pitched squeal of brakes?

A)
B)
C)
D)

Explanation:
The short, spread out sized wave of low-pitched, soft sound is going to change to a tall rather squished-looking wave as is seen in choiceA.

24)

Based on the images seen here, identify which phase of matter would transmit sound waves the fastest, and why?

A) / The gas would transmit the fastest because the particles move the fastest.
B) / The solid would transmit the fastest because the particles are closest together.
C) / The liquid would transmit the fastest because the particles are the most freely moving.
D) / The gas would transmit the fastest because there are the fewest particles to interfere with the waves.

Explanation:
The solid would transmit the fastest because the particles are closest together.Sound energy can transmit from one particle to the next quicker if the particles are close together.

25)

In the old west, a cowboy would put their ear on the railroad track to determine if a train was coming. Using this method, they could tell if the train was coming sooner than just listening for the train.

A good explanation for this would be that

A) / sound and vibrations travel faster through gases than solids.
B) / sound and vibrations travel faster through solids than gases.
C) / sound and vibrations dissipate faster in solids than in liquids or gases.
D) / sound and vibrations are more concentrated in solids than in liquids or gases.

Explanation:
The speed of sound is dependent on medium.Sound and vibrations travel faster through solids than gases.

26)If your new bike is painted so that it looks red, what color of light is reflected by the paint?

A) / blue
B) / indigo
C) / red
D) / violet

Explanation:
Theredlight waves are reflected.
If any colors of light are reflected by an object then that object will look the same color as the reflected light.

27)A high school website directs parents to not allow student access to blue laser pointers or allow the students to bring them to school. It includes a video describing the danger inherent in the misuse of all laser pointers particularly the blue laser pointer. Why would they claim that blue laser pointers are more of a concern than red laser pointers?

A) / Colored light falls into the visible region and the red light has a smaller wavelength and higher energy than blue light.
B) / The wavelengths and energies differ. The ultraviolet blue light has a larger wavelength and smaller energy compared to infrared.
C) / Both wavelengths fall into the visible light region but blue light has a smaller wavelength and higher energy than red light.
D) / These colors have similar wavelengths but the blue laser light has more energy than red laser light making it more dangerous.

Explanation:
Both wavelengths are fall into visible light region but blue light has a smaller wavelength and higher energy than red light.

28)A remote control only works when it is pointed at the television. What is the best explanation for this?

A) / The remote control has a weak signal and will only work over short distances.
B) / The remote control transmits information at the speed of light to the television.
C) / The remote control transmits information that is encoded and the television decodes it.
D) / The remote control transmits information through waves, such as infrared waves, to the television.

Explanation:
The remote control transmits information through waves, such as infrared waves, to the television..So, there must be a line of sight from the remote to the television.

29)A Wi-Fi hotspot is an area with an accessible wireless network. The term is most often used to refer to wireless networks in public areas like airports and coffee shops. Some are free and some require fees for use, but in either case they can be handy when you are on the go. Just like cellphones and televisions, wi-fi works by utilizing ______to transmit signals and data.

A) / radio waves
B) / microwaves
C) / ultraviolet rays
D) / infrared waves

Explanation:
Wi-fi works by utilizingradio wavesto transmit signals and data.
Communication across a wireless network is a lot like two-way radio communication. Here's what happens:
1) A computer's wireless adapter translates data into a radio signal and transmits it using an antenna.
2) A wireless router receives the signal and decodes it. The router sends the information to the Internet using a physical, wired Ethernet connection.

30)

Mary's class is studying sound waves. Mary played two sounds on her flute. For the first sound, Mary blew gently. For the second sound, Mary blew into the flute with a lot of force. What change can you hear?

A) / The second flute sound is louder than the first.
B) / The first flute sound has a higher pitch than the second.
C) / The two flute sounds are the same because they are the same note.
D) / The second flute sound has a lower pitch and is louder than the first sound.

Explanation:
The second flute sound is louder than the first.The wavelengths are the same so the pitch or note does not change. The amplitude is greater for the second sound so it is louder.

31)

Examine the pattern of the wave shown. What is true about the amplitude and wavelength of the wave when the pattern changes?

A) / Both the amplitude and wavelength of the wave increase.
B) / Both the amplitude and wavelength of the wave decrease.
C) / The amplitude of the wave increases while the wavelength decreases.
D) / The amplitude of the wave decreases while the wavelength increases.

Explanation:
The amplitude of the wave increases while the wavelength decreases.
Wavelength is the distance between one crest or trough to the next and amplitude is the height of the wave from the point of equilibrium.

32)The harder you strike a drum, the greater the sound’s

A) / medium
B) / volume
C) / frequency
D) / pitch

Explanation:
The correct choice isvolumebecause it is the loudness of a sound.

33)A student looks at ocean waves coming into the beach. An ocean wave with more energy will

A) / have a greater height.
B) / have a greater period.
C) / travel toward the beach faster.
D) / strike the beach with greater frequency.

Explanation:
The energy of a wave is proportional to the amplitude and willhave a greater height.

34)In the military, night vision goggles are used to pull off secret missions into areas that are very dangerous. For this reason, the soldiers try to infiltrate at night so they can't be seen. Thermal-imaging devices are often used as well to locate people on these highly secretive missions. What type of electromagnetic radiation is being utilized?

A) / radio waves
B) / gamma rays
C) / ultraviolet rays
D) / infrared waves

Explanation:
Infrared wavesare used in thermal-imaging devices as well as night vision cameras. They utilize the heat that is given off by humans to transmit information and get a picture of where they are at.

35)

A concave lens has an inward curved shape. It refracts light outward from the lens. The light rays spread apart as they exit the lens. Which represents a concave lens?

A) / A
B) / B
C) / A and B
D) / neither A nor B

Explanation:
A concave lens has a shape likeB. The lens has a curved inward shape.