Notes: Name: __________________________

Stamps:

NOTES OPTICS - REFRACTION

Directions: Fill in the blanks and boxes in the note panel. After notes are done, part of your homework is to fill in the sides with study questions and write a summary that demonstrates you understand what is important in the notes.

RefractionStudy Questions Main Notes

Refraction: The _______________ of ___________ when passing

through a new transparent substance.

Refraction Diagram

_______________________

_______________________

_______________________

_______________________

_______________________

Optical Density:

How ____________ it is for light to _________________ a substance.

High Optical Density:

Light travels through a substance _________________.

Low Optical Density:

Light travels through a substance _________________.Types of Refraction:

1

Low to High Optical Density:

FST: Fast to Slow, ____________the normal

o FAST

Low to much Higher

High to Low optical density

SFA: Slow to Fast ____________from the normal

Summary:

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Snell’s LawStudy Questions Main Notes

• As light travels through different substances, its ___________ changes.

• n is the ratio of old to new ___________

• n = _________________, also known as index of refraction

• c = ___________________ in a vacuum (____________ m/s)

• v = speed of light in a _____________

1. In what substance above will light travel the slowest in?

2. In what substance above will light travel the fastest in?

• Since light is fastest in space, n ≥ ___, always!

Values of n for different substances

3

3. Which substance in the picture below has the greatest optical density? Explain your reasoning.

Is the difference between the optical density of air and a vacuum significant?

In a vacuum: n ______

In air: n ______

• The majority of the time, the difference is so small that air is treated like a ___________

Trig Review:

SOH CAHTOA

sin θ =

sin−1 [sin (θ) ]=θ

θ =

4

Snell’s Law:

n1

1 incident angle

n2

2

How to choose the equation:

1. n =

Use to find ___________________

2.

Use to find ___________________

Example 1:How fast is light in water? (n for water is _______) Given:

Example 2:A ray of light passes from water to quartz. The angle of incidence in water is 35.0°. What is the angle of refraction?

Given:

5

Example 3:The photo below shows a smaller beaker inside a larger beaker. Wesson oil was poured into the larger beaker until it flowed about half way up the smaller beaker. Explain why the bottom of the beaker has disappeared.

Example 4:The speed of light in a certain substance is 1.90 x 108 m/s. If light passes from air into the substance at an angle of incidence of 54.0°, what will be the angle of refraction?

Given:

Summary:

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Why Does Light Bend?Study Questions Main Notes

There are two ways to explain

1st way: “Hikers and swamp”

• A row of hikers walking from dry land to swamp

• Once the Hikers hit the swamp

they __________________

• The hikers that haven’t hit the

swamp yet stay _____________

• This results in a changed ___________

2nd way: “The Fastest Path”

• dashed line is in slowsubstance for ________time and in fast substancefor _________ time

• Bent path is ____________

Summary:

SWAMP

DRY

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Total Internal Reflection How far can light bend?

The i that causes r = 90°, is called the ________________

Total Internal Reflection Conditions

Sometimes light reflects instead of refracts!

Only possible when light travels from ___________ to _________

because light needs to bend away from the normal.

Occurs when the __________angle _________ angle

i > ic

Checkpoint: Assume the critical angle for glass is 46°.

1. What will happen to a light ray traveling from glass to air which strikes the boundary at 40°?

2. What will happen to a light ray traveling from glass to air which strikes the boundary at 50°?

3. What will happen to a light ray traveling from air to glass which strikes the boundary at 50°?

4. What will happen to a light ray traveling from glass to air which strikes the boundary at 46°?

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Calculating the Critical Angle

Use Snell’s Law: solve for the incident angle when the reflected angle = 90°

Example: What is the critical angle for glass? (n = 1.50)Given:

Summary:

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White Light Dispersion

Light refracts differently for each _____________

The separation of light into its different colors is known as ___________

White Light Dispersion is the separation of white light into its ________

Rainbows are caused by dispersion!

Summary:

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Lenses

___________________ lens ___________________ lens

Lens Ray PatternsConverging Lenses

Parallel RaysRefract throughthe focal point

From fRefract parallel

Through Centerrefract straightthrough!

Diverging Lenses11

Parallel Raysgo away from f!

Towards fGo parallel

Through Centergo straight through!

Find the Image

Possible Regions:

___________________________ ___________________________

___________________________ ___________________________

Summary:

Thin Lens Equations12

focal point equation

Other forms:

Focal Lengthconverging lensdiverging lens

Image DistanceImage on same side as objectImage on opposite side as object

Magnification

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Multiple Lenses

go to pg. 92 to practice!

Summary:

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