Question 1

What happens to 
light when it strikes 
a metal surface?

Accepted Answer

Almost all of the energy is 
reflected back.

Question 2

What happens to 
light when it strikes 
glass or water?

Accepted Answer

Some of the energy is reflected 
and some is transmitted through 
the glass or water.
 Water:  2% is reflected
 Glass:  4% is reflected

Question 3

When light strikes a 
flat mirror at a 
certain angle, predict 
the path of the 
reflected light.

Accepted Answer

Reflects at the same angle but in 
the opposite direction

Question 4

.When you view your 
image in a plane 
mirror, how far 
behind the mirror is your image 
compared with your 
distance in front of 
the mirror?

Accepted Answer

Same distance behind the mirror 
as the objecvt is in front.
 Object distance = image 
distance

Question 5

Does the law of 
reflection hold for 
diffuse reflection?  
Explain.

Accepted Answer

Yes.  Every individual ray folows 
the law of reflection.  But incident 
rays hit many different-angled 
surfaces which causes reflection in 
many different direciton.

Question 6

Contrast the 
reflection of light 
from a rough and a 
smooth surface.

Accepted Answer

r- Rays of light striking this 
surface enounter many different 
flat surfaces facing in all 
directions so light rays are reflect 
in many different directions.
S-Rays of light strike at all 
the same angle and reflect at all the same direction

Question 7

What is meant by the idea that a surface 
may be polished for 
some waves and 
rought for others?  
Give an example.

Accepted Answer

if the difference in elevations of the surface are less than 1/8 the 
length of the light wave, the  
surface is considered smooth.
 Piece of paper is considered 
smooth for a long radio wave, 
but rought for a short light 
wave.

Question 8

What is the effect on 
sound when room 
surfaces are too 
reflective?  Too 
absorbent?

Accepted Answer

Too reflective :  garbled sound
Too absorbent:  sound is dull and 
lifeless.

Question 9

What could an 
acoustical engineer 
do in designing a 
room to reduce the 
sound level?

Accepted Answer

Count use soft, absorbent 
materials so that some of the 
sound waves are absorbed.

Question 10

How are reflection 
and refraction alike?  
How are they 
different?

Accepted Answer

A- when waves reach a 
boundary of a new medium.Involve change in direction of a wave
D:Refl. occurs when the waves DONT go through the new medium but bounce back, 
refr. when the wave go into new medium. Refr: waves chng spd, refl: waves 
travel same

Question 11

When a wave 
crosses a surface at 
an angle from one 
medium into 
another, why does it 
“pivot” as it moves 
across the boundary 
into the new 
medium?

Accepted Answer

Wave pivots because the part of 
the wave that reaches the news 
medium first changes speed while 
the rest of the wave does not.

Question 12

What is the 
orientation of a ray 
in relation to the 
wave front of a 
wave

Accepted Answer

A ray is perpendicular to the wave front

Question 13

Why do sounds 
carry across a lake 
better at night than 
during the day?

Accepted Answer

Air near the ground is colder than 
the air above, so speed of sound is 
slower near the ground and faster 
in the warm air above causing the 
sound waves to bend toward the 
ground.

Question 14

What are 3 
examples of the 
effect of refraction 
that we can see?

Accepted Answer

 Stars twinkle
 Pencil appear bent in water
 Air above a hot stove appears 
to shimmer

Question 15

What are 3 
conditions that could 
cause refraction

Accepted Answer

Light waves change speed 
(refract) when light passes
 From one medium to another
 Through different 
temperatures of the same 
medium
 Through different densities of 
the same medium.

Question 16

Does refraction 
occur for both sound 
waves and light waves?

Accepted Answer

yes

Question 17

If light had the 
same speed in air 
and in water, would
light be refracted in 
passing from air into 
water?  Explain

Accepted Answer

No because refraction is caused by 
change in speed so
 No change in speed = no 
refraction

Question 18

If you can see the 
face of a friend who 
is underwater, can 
she also see you?  
Why?

Accepted Answer

Yes because the light paths are 
reversible for reflection and 
refraction.

Question 19

. Does refraction 
tend to make objects 
submerged in water 
seem shallower or 
deeper than they 
really are?

Accepted Answer

Shallower

Question 20

What happens to 
the speed of light as 
it goes from air to 
water?
Air  water:  light shows down
Which way does light bend as it 
passes from air to water?

Accepted Answer

Air  water:  light shows down
Air  water:  light bends toward 
the normalAir  water:  light bends toward 
the normal

Question 21

As light passes 
through glass or 
water, do the high or 
low frequencies of 
light interact more in 
the process of 
absorption and 
reemission and, 
therefore, slow down 
more?

Accepted Answer

High frequencies – b/c/ they are 
closer to the natural frequency of 
glass and water and, therefore, 
resonate more.
More interaction = slower speed

Question 22

Why does blue 
light refract at 
greater angles than 
red light in 
transparent 
materials?

Accepted Answer

Blue light (higher frequency) 
refracts (bends) more because it 
slows down more than red light.

Question 23

Describe the 
conditions necessary 
for a motorist to see 
a mirage.

Accepted Answer

The air near the surface must be 
very hot – light speeds up in the 
hot air and refracts upward.

Question 24

Explain how a 
prism separates 
white light into 
colors.  Include a 
diagram to illustrate 
your answer

Accepted Answer

Blue light slows down more than 
red so blue light is bent more than 
red.   When this happens twice (at 
the two nonparallel glass surfaces 
of a prism) the effect is enough to 
see the rays dispersed

Question 25

Describe the sky 
conditions necessary 
for a rainbow.  
Where must you be
to see the rainbow?

Accepted Answer

Sun must be shining in one part of 
the sky and water droplets from a 
cloud or falling rain in the 
opposite part of the sky.
You must be standing with your 
back to the sun.

Question 26

What are two 
factors that cause a 
diamond to 
“sparkle” and 
produce brilliant 
colors?

Accepted Answer

. Small critical angle of 
diamonds (24.6
o
)
2.Unusually low speed of light 
in diamonds (0.4 c)
These two factors cause light to be 
dispersed in a broad, intense 
sparkle

Question 27

Compare the 
critical angles of 
water, glass and 
diamonds

Accepted Answer

Water – 48
o
Glass -- 43
o
Diamonds – 24.6

Question 28

How much light 
leaves a medium if it strikes the boundary 
at an angle greater 
than the critical 
angle?

Accepted Answer

none

Question 29

Give 3 specific 
examples of uses for 
optical fibers.

Accepted Answer

Mechanics use them to look inside 
engines.
Physicians used them to look 
inside a patient’s body.
Communications:  replace copper 
telephone wires and underseas 
cables (more information can be 
carried on by high frquency light 
than by low freq

Question	Answer
What happens to light when it strikes a metal surface?	Almost all of the energy is reflected back.
What happens to light when it strikes glass or water?	Some of the energy is reflected and some is transmitted through the glass or water.  Water: 2% is reflected  Glass: 4% is reflected
When light strikes a flat mirror at a certain angle, predict the path of the reflected light.	Reflects at the same angle but in the opposite direction
.When you view your image in a plane mirror, how far behind the mirror is your image compared with your distance in front of the mirror?	Same distance behind the mirror as the objecvt is in front.  Object distance = image distance
Does the law of reflection hold for diffuse reflection? Explain.	Yes. Every individual ray folows the law of reflection. But incident rays hit many different-angled surfaces which causes reflection in many different direciton.
Contrast the reflection of light from a rough and a smooth surface.	r- Rays of light striking this surface enounter many different flat surfaces facing in all directions so light rays are reflect in many different directions. S-Rays of light strike at all the same angle and reflect at all the same direction
What is meant by the idea that a surface may be polished for some waves and rought for others? Give an example.	if the difference in elevations of the surface are less than 1/8 the length of the light wave, the surface is considered smooth.  Piece of paper is considered smooth for a long radio wave, but rought for a short light wave.
What is the effect on sound when room surfaces are too reflective? Too absorbent?	Too reflective : garbled sound Too absorbent: sound is dull and lifeless.
What could an acoustical engineer do in designing a room to reduce the sound level?	Count use soft, absorbent materials so that some of the sound waves are absorbed.
How are reflection and refraction alike? How are they different?	A- when waves reach a boundary of a new medium.Involve change in direction of a wave D:Refl. occurs when the waves DONT go through the new medium but bounce back, refr. when the wave go into new medium. Refr: waves chng spd, refl: waves travel same
When a wave crosses a surface at an angle from one medium into another, why does it “pivot” as it moves across the boundary into the new medium?	Wave pivots because the part of the wave that reaches the news medium first changes speed while the rest of the wave does not.
What is the orientation of a ray in relation to the wave front of a wave	A ray is perpendicular to the wave front
Why do sounds carry across a lake better at night than during the day?	Air near the ground is colder than the air above, so speed of sound is slower near the ground and faster in the warm air above causing the sound waves to bend toward the ground.
What are 3 examples of the effect of refraction that we can see?	 Stars twinkle  Pencil appear bent in water  Air above a hot stove appears to shimmer
What are 3 conditions that could cause refraction	Light waves change speed (refract) when light passes  From one medium to another  Through different temperatures of the same medium  Through different densities of the same medium.
Does refraction occur for both sound waves and light waves?	yes
If light had the same speed in air and in water, would light be refracted in passing from air into water? Explain	No because refraction is caused by change in speed so  No change in speed = no refraction
If you can see the face of a friend who is underwater, can she also see you? Why?	Yes because the light paths are reversible for reflection and refraction.
. Does refraction tend to make objects submerged in water seem shallower or deeper than they really are?	Shallower
What happens to the speed of light as it goes from air to water? Air  water: light shows down Which way does light bend as it passes from air to water?	Air  water: light shows down Air  water: light bends toward the normalAir  water: light bends toward the normal
As light passes through glass or water, do the high or low frequencies of light interact more in the process of absorption and reemission and, therefore, slow down more?	High frequencies – b/c/ they are closer to the natural frequency of glass and water and, therefore, resonate more. More interaction = slower speed
Why does blue light refract at greater angles than red light in transparent materials?	Blue light (higher frequency) refracts (bends) more because it slows down more than red light.
Describe the conditions necessary for a motorist to see a mirage.	The air near the surface must be very hot – light speeds up in the hot air and refracts upward.
Explain how a prism separates white light into colors. Include a diagram to illustrate your answer	Blue light slows down more than red so blue light is bent more than red. When this happens twice (at the two nonparallel glass surfaces of a prism) the effect is enough to see the rays dispersed
Describe the sky conditions necessary for a rainbow. Where must you be to see the rainbow?	Sun must be shining in one part of the sky and water droplets from a cloud or falling rain in the opposite part of the sky. You must be standing with your back to the sun.
What are two factors that cause a diamond to “sparkle” and produce brilliant colors?	. Small critical angle of diamonds (24.6 o ) 2.Unusually low speed of light in diamonds (0.4 c) These two factors cause light to be dispersed in a broad, intense sparkle
Compare the critical angles of water, glass and diamonds	Water – 48 o Glass -- 43 o Diamonds – 24.6
How much light leaves a medium if it strikes the boundary at an angle greater than the critical angle?	none
Give 3 specific examples of uses for optical fibers.	Mechanics use them to look inside engines. Physicians used them to look inside a patient’s body. Communications: replace copper telephone wires and underseas cables (more information can be carried on by high frquency light than by low freq

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CHAPTER 29 YEAH