Chapter 11

How does light penetrate a pane of glass?

Electrons in atoms of glass are forced into vibration. Energy is momentarily absorbed and vibrates electrons in the glass. A vibrating electron either emits a photon or transfers the energy as heat. Light slows due to time delay between absorption and reemission of photons.

T or F: Light changes frequency upon reflection.

False, does not.

T or F: Sound can be polarized.

False.

When light shines on metal and sets free electrons into vibration, their energy does not "spring" from atom to atom in the material. What actually happens?

It is reflected.

How is the transmittal of light similar to sound?

Light incident on matter forces some electrons in matter to vibrate.

Electromagnetic waves created by vibrating electric charges having frequencies that fall within the range of sight. What is this?

Light.

What is an electromagnetic wave made of?

Made up of vibrating electric and magnetic fields that regenerate each other by electromagnetic induction.

______ things absorb light without re-emission.

Opaque

State the law of reflection.

The angle of reflection equals the angle of incidence.

How does diffuse reflection help you see the road at night?

The diffuse reflection of illumination from your car headlights lets you see road ahead at night. Rough road surface is necessary for this. When road is wet, harder to see!

T or F: Compared with the primary rainbow, the secondary bow is dimmer, has colors reversed, is caused by two internal reflections.

True.

T or F: Electric and magnetic fields can induce each other.

True.

T or F: Glass is transparent to all the frequencies of visible light.

True.

T or F: The atmosphere is opaque to high-frequency ultraviolet light.

True.

T or F: When white light passes through a prism, green light is bent more than red light.

True.

When does diffuse reflection occur?

When light is incident on a rough surface and reflected in many directions.

Polarized light would be represented by ________.

a single vector

Glass _______ UV light.

absorbs

Which of these would not exist if light didn't slow in transparent materials: rainbows, mirages, magnifying glass?

all wouldn't exist

When you stand 2 meters in front of a plane mirror, your image is __ meters from you & __ meters in back of the mirror.

2, 4

An ideal Polaroid filter transmits ____% of incident unpolarized light.

50

What causes the bending of the wave (sound or light)?

A change in speed.

In _________ mirrors, virtual image is larger and farther away than the object.

concave

All the drops that disperse the rainbow's light toward you lie in the shape of a _____.

cone

In ________ mirrors, virtual image is smaller and closer to the mirror than the object.

convex

Know as light travels through a ________ medium, it will slow down.

denser

In _______ reflection, light striking a rough or irregular surface reflects in many directions.

diffuse

Rainbows are colorful examples of ___________.

dispersion

This separation of light into colors arranged by frequency is called _________.

dispersion

What is the process of the separation of light into colors arranged by frequency?

dispersion

An ________ field is induced in any region of space in which a magnetic field is changing with time.

electric

Light travels _______ through the thinner hot air near the surface than through the denser cool air above.

faster

The frequency of re-emitted light passed from molecule to molecule is identical to the _________ of the original light that produced the vibration.

frequency

Frequency of vibrating electrons equals the frequency of the ______.

light

Infrared waves have frequencies _______ than those of visible light.

lower

A _______ field is induced in any region of space in which an electric field is changing with time.

magnetic

Metals are _______ to visible light.

opaque

Convex mirrors curve _________, concave mirrors curve ________.

outward, inward

Most glare from nonmetallic surfaces is ________.

polarized

If the axes of two polaroid filters are at right angles to each other (in this case, we say the filters are crossed), almost no light penetrates the pair When Polaroid filters are used in pairs like this, the first one is called the _________ and the second one is called the ________.

polarizer, analyzer

A photographer wishes to photograph a lightning bolt by setting a camera so that it is triggered by the sound of thunder, is this a good idea or poor idea?

poor idea

Unless the light is perpendicular to the surface of penetration, bending occurs. This is the phenomenon of ___________.

refraction

When ultraviolet rays in sunlight shine on glass, _________ occurs as the wave builds and maintains a large amplitude of electron vibration.

resonance

Reflections going back the reverse ways of the first reflection itself can cause __________.

secondary rainbows

Refracted light that bends toward the normal is light that has ______ _____.

slowed down

A light wave incident on a pane of glass sets up vibrations in the molecules that produce a chain of absorptions and re-emissions, which pass the light energy through the material and out the other side. Because of the time delay between absorptions and re-emissions, the light travels through the glass more ________ than through empty space.

slowly

Refracted light that bends away from the normal is light that has _____ ___.

sped up

A rainbow always faces you _________.

squarely

What is polarization (light)?

the alignment of transverse electric vectors in electromagnetic waves

If violet light from a single drop reaches an observer's eye, red light from the same drop is incident elsewhere toward _______.

the feet

Materials such as glass and water allow light to pass through without absorption, usually in straight lines. These materials are _________ to light.

transparent

Light and all electromagnetic waves are ________ waves.

transverse

Polarization occurs for waves that are __________.

transverse

Polarization occurs only for __________ waves.

transverse

Sound waves refract when parts of the wave fronts... (3).

travel at different speeds, are affected by uneven winds, when air near ground is warmer than air above

Vibrating electrons emit most electromagnetic waves. When light is incident on matter, some of the electrons in the matter are forced into ________.

vibration

What is true of unpolarized light?

vibrations producing light are in all directions (not going in a specific direction)

Thee electromagnetic spectrum spans waves ranging from lowest to highest frequencies, the smallest portion of the electromagnetic spectrum is that of __________.

visible light

When does minimum angle occur?

when a ray of light comes exactly in the middle (no refraction)

___________ refraction is the cause of refractions.

Atmospheric

When you face a rainbow, where is the Sun?

Behind you, in the opposite part of the sky.

State the Law of Reflection.

Angle of incidence = angle of reflection

How does a curved mirror behave?

As a succession of flat mirrors.

How do we see a rainbow?

1 rainbow requires moisture in the air 2 sunlight will enter into the drop of water; as it goes from air to water = refraction will bend it 3 blue and the red are refracted differently; they bend differently 4 refraction - reflection - refraction happens when the sunlight is going through raindrop 5 angle differences cause red to bend ahead of violet

_________ is the returning of a wave to the medium through which it came when encountering a reflective surface.

Reflection

_______ is the bending of light when it passes from one medium to another.

Refraction

Whenever we watch a sunset, we see the Sun for several minutes after it has sunk below the horizon. What causes this?

Refraction!

A single vibrating electron can emit an electromagnetic wave that is plane polarized. The plane of polarization matches the vibrational direction of the electron. What does this mean?

That a vertically accelerating electron emits light that is vertically polarized. A horizontally accelerating electron emits light that is horizontally polarized.

What must occur for you to see a rainbow?

The Sun must shine on drops of water in a cloud or in falling rain. The drops act as prisms that disperse light.