Day 1 Refraction May 4th Friday
Today I mentioned that if you would like to come in on your own time and retake the last test (no notes and test is different than the first one) that you could by the end of the day next Tuesday.
We had to finish up that Problem 2 sheet from the last unit quick and take a quick look at the calendar for May before starting the new unit on refraction.
Next we took a quick look at the May calendar.
We had to finish up that Problem 2 sheet from the last unit quick and take a quick look at the calendar for May before starting the new unit on refraction.
Next we took a quick look at the May calendar.
| mayjune2012.pdf |
Next we took a quick look at the objectives for Unit 11 on Refraction, especially the labs.
| refraction_objectives.pdf |
Next we started the first of three problem sheets called The Bending of Light.
| the_bending_of_light_problem_sheet.pdf |
The Hands on to aid in answering a question on the above problem sheet later.
The hands-on was a glass of water with a pencil in the glass at each seat for students to see how the pencil refracts (bends) as the pencil enters the water.
The Disappearing Beaker Demo
The demonstration was having a student poor Baby Oil in a medium beaker of water that had a much smaller beaker sitting inside it. As the oil filled the smaller beaker and overflowed into the larger beaker the smaller beaker disappeared until the oil was over the smaller beaker and it was gone all together.
The hands-on was a glass of water with a pencil in the glass at each seat for students to see how the pencil refracts (bends) as the pencil enters the water.
The Disappearing Beaker Demo
The demonstration was having a student poor Baby Oil in a medium beaker of water that had a much smaller beaker sitting inside it. As the oil filled the smaller beaker and overflowed into the larger beaker the smaller beaker disappeared until the oil was over the smaller beaker and it was gone all together.
Day 2 Refraction Effects The Eye May 7th Monday
First topic was the outstanding Show Time program this last weekend. WOW! The singing, dancing, and musicians were all superb. The songs chosen were also fantastic (even the ones I had never heard of). I will try to buy a DVD and/or CD of the performance ASAP.
Secondly, we ran the following power-point:
Secondly, we ran the following power-point:
| refractioneffectseye.ppt |
and we finished #3, 4, 5, and 6 on our problem sheet.
| the_bending_of_light_problem_sheetpd4.pdf |
The key points today were: 1). The higher the index of refraction of an optical transparent material (like air, water, glass, diamond) the more it slows down light and the more a ray of light is bent toward the normal. To calculate the index of refraction one uses Snell's Law.
You can play with refraction in the following PHET simulation site:
Bending Light
You can play with refraction in the following PHET simulation site:
Bending Light
or can try the following site for notes on Snell's Law the way we use it (but the following site can also be used to check your work)
Snell's Law Notes
or this site does Snell's Law with the angles and the velocities
Snell's Law with Velocities & angles
Day 3 Ray Diagrams May 8th, 2012 Tuesday
Today we handed out the ray diagram sheet below but it had the same diagram on each side of the handout where like the last unit we did one side together in class and the other side was for homework due this Thursday.
| lensdiagrams.pdf |
Here are the smart board notes from period 6
| lensdiagramspd6.pdf |
Then depending on the period, we finished the Bending of Light sheet:
| the_bending_of_light_problem_sheet.pdf |
Both 6th and 8th period finished. Here is 8th period's smart board presentation.
| bendingoflightpd8b.notebook |
Tomorrow and the next day we have a two day lab.
Day 4 Refraction of Light Lab May 9th Wednesday
Today we finished up the Bending of Light Homework sheet first because you need to understand how to do problems 9 & 10 in order to do the lab. Here is the smart board work from a morning class
| the_bending_of_light_problem_sheetpd4.pdf |
Then we broke into lab groups of three and one group volunteered to show part 1 and another group part 2 of the lab as I explained it.
Here is the lab handout:
Here is the lab handout:
| refractionlab.pdf |
Part 1 is calculating the index of refraction of water ( n = 1.333) by shining a laser into an beaker and marking on the vertical piece of masking tape down the outside where the laser light hit. Then pouring water above the laser light mark and marking the top of the water and the first refracted laser light position and then filling the beaker and marking again the laser light and the top of the water level. Taking the ratio of 1 to 1 over empty and the lower water level and again from 2 to 2 and the distance between the 2's gives you a little over 1.333.
Part 2 is tracing a rectangular piece of glass, plastic, or specimen sample and having a laser light hit one side and come out the second side and measure all four angles. Then using Snell's law to calculate the index of refraction twice (once entering the unknown, and once leaving the unknown.
We'll finish parts 1 and 2 tomorrow and start part 3 on curved lenses
Part 2 is tracing a rectangular piece of glass, plastic, or specimen sample and having a laser light hit one side and come out the second side and measure all four angles. Then using Snell's law to calculate the index of refraction twice (once entering the unknown, and once leaving the unknown.
We'll finish parts 1 and 2 tomorrow and start part 3 on curved lenses
Day 5 2nd Day of Refraction Lab May 10, 2012
The following power point will aid you in understanding what you have to do for all three parts of this lab:
| refraction_lab.pptx |
And here is a pdf version of the same power point (in case you do not own the power point software)
Great America preparation next Monday but you should start finding a group of 3 or 4 NOW! Also read the following for all the other things you need to know.
| refraction_lab.pdf |
And here is the lab again and data table examples for the lab if you didn't get it above.
| refractionlab.pdf |
| refraction_lab_data_tables.pdf |
Day 6 Two way mirrors May 11th Friday
They make mirrors by simply silvering one side of a piece of glass so if you rub off some of the back of the mirror you'll have a piece of glass you can see through again. However, a two way mirror is only half silvered so half is mirror and half is glass. Now the lighting is what is of next importance as you need it really bight on the mirrored side and dark on the back side. Thus the people on the mirrored side are only seeing the mirrored image reflected but those in the back (in the dark) have the light shining through the half glass and can see through the mirror. If you turn on the light in the back or turn off the lights on the front side, you only have a piece of glass.
If you wish to read a short website explaining how they make two way mirrors go to:
How they make two way mirrors.
If you wish to read a short website explaining how they make two way mirrors go to:
How they make two way mirrors.
We also explained that wet sand is dark because light reflects off dry sand much better and refracts into the wet sand thus not reflecting as well making it darker. We did the demo in class.
We also explained how transition lenses work and did a demo where we blocked part of the transition lenses (photogray) with paper and then set it on a bright light or the sunshine for a few minutes so when we took the piece of paper off the glasses retained the shape as lighter than the darker rest of the eye glass due to the chemical reaction that took place where the ultra-violet light stimulated the reaction.
Then we worked on hocus-focus home work sheet until there was only 20 minutes remaining to complete the Refraction Lab
Here are some of the smart board work done, period by period, on Hocus-Focus
| hocus_focuspd1.pdf |
| hocus_focuspd4.pdf |
| hocus_focus_pd6.pdf |
Here are two files about Great America next Friday that would aid reading today for your planning for Great America next Tuesday.
| welcome_to_great_america.pdf |
| physics_great_america_2012.docx |
Day 7 Preparing for Great America
Today we determined the height of the SPASH flagpole using our eye height (e) and the distance between two angles taken by taking the first angle and walking directly away from the flagpole and taking a second angle. We figured out the angles using a sextant to determine the angle between a horizontal from our eye and the top ball on the flagpole (theta sub 1) and walking a distance b directly away from the pole (on a flat surface) and taking the second angle. The formula used for the distance and a diagram is right on the front of the sextant:
Front of the sextant:
Front of the sextant:
| front_of_sextant.pdf |
and all the formulas we may need to do the Great America Lab are on the back of the sextant
| back_of_sextant.pdf |
We also measured our pace by walking along a tape measure on the floor. For example: My pace was 11 comfortable normal steps ended up at about 8 meters every time so I'd use 8 meters for my b in the formula (which is the distance I walked away from the flagpole before taking the second angle measurement. Also note that at zero degrees the sextant reads 90 degrees meaning you need to take the complement (which angle adds to 90 degrees) of the angle you read on the sextant (so if the sextant says 51 degrees you use 39 degrees in the formula).
Here is the half sheet that everyone did their own calculation of the flagpole height and turned in before they left class today.
Here is the half sheet that everyone did their own calculation of the flagpole height and turned in before they left class today.
| height_of_spash_flagpole.pdf |
Now those that were going hto Great America tomorrow picked up the following handout to take with. Before tomorrow they are suppose to pick two of nine labs (listed on the back of the handout, and maybe a third one in case one of the two they pick are not open yet tomorrow.) and collect the data from www.sixflags.com website.
Here is the handout for those going to Great America:
Here is the handout for those going to Great America:
| great_america_lab_for_those_who_go.pdf |
Then for those who could not go we handed out the following sheet with two rides for them to check out before tomorrow,
| stay_home_great_america_lab.pdf |
HERE IS A COPY OF THE BRIEFING GONE OVER BEFORE LEAVING FOR GREAT AMERICA. Write down anything on the list you need to remember to bring.
| six_flags_great_america.docx |
Finally, as we walk into the park they read the following to everyone on the bus before departing the bus.
| welcome_to_great_america.pdf |
See all that are going before 5:25 am tomorrow by the flagpole for the 5:30 departure.
Day 8 Lens Lab
Today we mentioned Great America Lab Requirements first. You may skip two items on the scavenger hunt for Great America numbers 5 & 8 because there is no more Iron Wolf and they painted over the numbers on the fire station.
| lens_lab.pdf |
Day 9 TIR
TIR stands for Total Internal Reflection. We explained that only when light travels from a more dense medium to a less dense medium can you get it to totally reflect at this critical angle or an angle greater than the critical angle. You see, as light leaves, let's say, water into air; the light bends away from the normal. If you keep increasing the angle of incidence, sooner or later the angle of refraction will be 90 degrees. That incident angle is your critical angle. So if you take Snell's Law n1sin(i) = n2sin(r) and make angle r = 90 degrees it drops out as the sin 90 = 1
Day 10 Mirages and Rainbows
Inferior mirages (like seeing a water pudding up ahead on a black road or hot sand in the desert) are caused by cool air above hot air. When there is a real water puddle, light from the sun reflects off it to your eyes, so when light bends away from the normal as light goes from cool air (higher index of refraction) to hotter air (lower index of refractions) it continuously bends and hits your eyes. The brain figures that it must be water up ahead.
Superior mirages are similar only they are above you and are caused by cooler air below (like Lake Michigan in the spring) and warmer air above the cooler air. Once lights in Michigan refracted to Milwaukee and people in Milwaukee could see across the about 90 miles of lake to lights in Michigan.
The lower rainbow is caused by light (if the angle is just right) refracting into raindrops and reflecting once on the far side of the raindrop back to your eyes. In the mean time the white light refracts differently (called dispersion as the white light breaks up, or disperses, into all the colors that make up white light (mainly ROY G BIV). The second rainbow is formed from higher droplets of water refracting the light and reflecting twice within the droplets back to your eyes. Because of two reflections internally in the droplets of water the colors are upside down with the Violet at the top.
Superior mirages are similar only they are above you and are caused by cooler air below (like Lake Michigan in the spring) and warmer air above the cooler air. Once lights in Michigan refracted to Milwaukee and people in Milwaukee could see across the about 90 miles of lake to lights in Michigan.
The lower rainbow is caused by light (if the angle is just right) refracting into raindrops and reflecting once on the far side of the raindrop back to your eyes. In the mean time the white light refracts differently (called dispersion as the white light breaks up, or disperses, into all the colors that make up white light (mainly ROY G BIV). The second rainbow is formed from higher droplets of water refracting the light and reflecting twice within the droplets back to your eyes. Because of two reflections internally in the droplets of water the colors are upside down with the Violet at the top.
Day 11 Review Day
Below are the review sheet for the day and the answer key to the review sheet under it. Also, look over all the handouts and labs for the unit. The test is 25 Multiple Choice worth 2 points apiece and any four of seven problems on a separate sheet worth three points apiece (any extra problems done worth extra credit). Total of 62 points for test with max of 7 pts. extra credit.
| reviewsheetfollowedbyanswers.pdf |
And in case you did not get hocus focus done, here are Amber O.'s notes to help you out.
| hocusfocusanswers.pdf |