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Please grab your calculator What is the: Sin 30 o.5 Sin 45 o.71 Sin 22 o.37 Sin 35 o / sin 55 o.7

Physics Journals Date Table of contents page # Semester 2 1/7Conservation of Momentum? 1/14Sounds in Vibrating Strings? 1/21Making Waves? 1/28Sounds in Strings Revisited? 2/3Sounds From Vibrating Air? 2/11Shadows and Color Addition? 2/13Reflected Light? 2/19Curved Mirrors? 2/26Refraction of Light?

Homework: Due Tuesday /Wednesday Read PT pg CU pg 562 #1 PTG pg 565 #1,3,6,7,8 Honors include: #9,10

CLO: SW explore refraction, Observing and then writing an explanation as to what is meant by “Index of Refraction” and what happens as light travels from a less optically dense medium to a more optically dense medium.

Section #8 Refraction of Light pg 558,

Materials: #1 -7 -acrylic block -protractor -pencil -calculator -laser -straight edge

#1-6: What I want to see Copy data table pg 559 Skip the graphing part but calculate the ratio of the sin of angle Incidence to the sin of the angle of refraction for each trial Finish this statement: The ratio of the sin of angle of incidence to the sin of angle of refraction was the same or different for all three trials.

Do now: 1. A flagpole is casting a shadow as shown in the diagram. Which of the following would make the length of the shadow shorter? a) Increasing the height of the flagpole. b) Moving the Sun in the vertical direction “up”. c) Making the Sun brighter. d) The Sun in the vertical direction “down”. 2. The diagram below shows a light ray striking a concave mirror parallel to the principal axis. Point C is the center of curvature of the mirror, and point F is the principal focus. The light ray will reflect through which point? 3.If an image distance is negative, is it real or virtual? 4. If an object height is – is it real or virtual?

Let’s look at the data you gathered last week from 4 groups 3groups: Angle of incidence Angle or refraction 1) 39 o 25 o 2)23 o 15 o 3)32 o 20 o 4)45 o 27 o For each data set, divide the sin i by the sin r : sin i sin r

CLO: SW define refraction, Dispersion, and index of refraction, and Snell’s law. Being able to identify, write out and solve problems involving the application of Snell’s Law.

The ratio of the sin of angle of incidence to the sin of angle of refraction was the same or different for all three trials. Crucial Physics: How does light refract when going from less to more optically dense media? -car in mud scenario -camping at a lake scenario

Let’s take some notes!

Refraction Dispersion of Light Index of Refraction Defined: Examples: Visual: Law of Refraction (Snell’s Law) Defined: Equation:

Refraction the change in direction of a propagating wave (light or sound) when passing from one medium to another

Let’s look at a prism, why do we see all the colors? Shoulder partner share-out Let’s see what Bill Nye says (first min) E&feature=related

Dispersion ROYGBIV Higher frequencies of white light refract more

Index of Refraction n Defined: “n” A transparent materials ability to bend light Examples: Air or vacuum n=1.0 Acrylic n= 1.5 Water n= 1.3 Diamond n=2.4 Visual:

n=1.0 i n=1.3 r

Concept Check: Light enters the following substances at an angle, what happens to the light as it goes from one substance to another. n= 1.0 n= 1.7 n= 1.0 n= 1.2 n= 1.5

. n= 1.0 n= 1.7 n= 1.0 n= 1.2 n= 1.5

Law of Refraction (Snell’s Law) Defined: The index of refraction of a material is equal to the ratio of the sin of the angle of incidence to the sin of the angle of refraction. Equation: n= sin i sin r

Take a break, and put down your pencil n i sin i = n r sin r My favorite equation to say out loud

Snell’s Law w/ a bit more detail n i sin i = n r sin r n i = Index of refraction of incident medium n r = Index of refraction of substance light enters sin i = sin of the angle of incidence sin r =sin of the angle of refraction (if the incident medium is air n i is 1) Therefore: n r = sin i / sin r So, as light travels from one medium to another we use Snell’s law: n i sin i = n r sin r

Law of Refraction (Snell’s Law) Defined: The index of refraction of a material is equal to the ratio of the sin of the angle of incidence to the sin of the angle of refraction. Equation: In a vacuum or air n= sin i sin r or n i sin i = n r sin r

What happens if two objects have the same index of refraction? Pyrex and Baby Oil

Grab your calculators please

1. In the picture below, the incident beam from air (n=1) has an angle of incidence of 30 o The refracted ray has an angle 22 o to the normal. What is the index of refraction for the material the light is entering? 1.33

2. A ray of light is incident at an angle of 40.0 o upon the surface of a diamond (n=2.4). What is the angle of refraction? 15.5 o

3. A block of material is submerged in water (n=1.33) light in the water is incident on the block at an angle of 31 o to the normal. The angle of refraction in the block is 27 o. What is the materials index of refraction? 1.47

Homework: Due next class Read PT pg CU pg 562 #1 PTG pg 565 #1,3,6,7,8 Honors include: #9,10

Do Now: 1. A student shines a laser into a fish tank as shown in the following diagram. On which of the fish in the diagram would the laser beam shine? 2.An object is placed at a distance greater than the center of curvature from a Concave mirror. Give three properties of the image that is formed. 3.If you want to double the speed of a roller coaster at the base of the 1 st hill, how much higher must you make the hill?

Collect Homework The following people missed the quiz last Thursday (shadows and reflection): Emma Connor Mia Vinnie Alejandra H Jalitza Andres Victoria Monica

refractive indices Vacuum1 (by definition) Air (at 0 °C, 1 atm) Water ice1.31 Water (at 20 °C)1.333 Glass Acrylic Sapphire1.762–1.778 Cubic zirconia Diamond2.419 Some common refractive indices (n):

Gather the data and calculate the index of refraction for Water and crown glass.

SW explore Total Internal Reflection, and apply a new equation to solving light refraction problems, demonstrating proficiency through “Practice Perfect”.

Another equation to find Index of Refraction! n r = speed of light in a vacuum or air speed of light in the material n r = C / v r Speed of light in a vacuum or air = 3.0 x 10 8 m/s What is the speed of light in a diamond (n=2.4)?

Index of refraction and speed of light Equation: n substance = C v substance C= 3.0x10 8 m/s

1-2-4 problems: 1.The speed of light in air is 3.0 x 10 8 m/s while the speed of light in glass is 2.0 x 10 8 m/s what is the index of refraction of the glass? A diamond has an index of refraction of 2.4, since you know the speed of light in air is 3.0 x 10 8 m/s, calculate the speed of light in a diamond x 10 8 m/s

Practice Perfect Snell’s Law 1.n r = n r = r= 35o 4.r=51o 5.r=28 o A=62 o B=58 o C=32 o D=53 o Glass= 41.8 o Diamond=24.6 o

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CLO: SW will explore total internal reflection of light, and observe what is meant by “critical angle”. Being able to define and diagram what happens when total internal reflection occurs.

Turn to page560 Materials needed: -Laser -Triangle prism Do # minutes By the end of the activity, be able to answer the following: -What is total internal reflection? -What is critical angle?

Critical angle and total internal reflection

Critical Angle Explained: When light goes from a more optically dense medium (incident medium) to a less optically dense medium (refractive medium) and makes an angle of refraction of 90 o Total Internal Reflection When the angle of refraction is greater than 90 o

Let’s draw it in our notes: Three colored pencils and straight edge

Which ray is characteristic of what will happen?

Baby Oil and Pyrex? Gel Beads? Penny in a bowl Fiber optics

Explain (you cannot just say “refraction” 1.Why are the optical properties of diamonds different then that of glass? 2.Why does the straw appear broken in the glass of water? 3.How do you explain the mirage on the road?

Practice Perfect Snell’s Law

Grab a ruler Draw the image formation for an object placed at the center of curvature for a concave mirror.