Optics

Vyassa says: Practice the laser shoot (if that's still a part of the event) under pressure. You might do it right 100 times in practice, but at the competition, you might screw something up because time is limited, and time counts. Optics is an event for divisions B and C . This event deals with geometric and physical optics, such as reflection, refraction, critical angle, electromagnetic and visible spectrum, lenses, and mirrors. Competitors for this event may bring any type of calculator and should have knowledge of SI units, as all answers will require a student to know and understand them. Some aspects of optics are similar to the former event Crave the Wave, though Optics focuses on light while Crave the Wave was about waves in general

Resources to use:
 * Textbook that AB Physics H uses
 * Binder that I left behind with Dempsey - there is some random notes I scribbled everywhere - pay attention to them.
 * Test I made for state testing - ask an officer for it.
 * Massive wikipedia'ing + lots of tests on the test exchange.

General Advice:

- What's tested is limited to the topics listed on the sheet, but simply knowing what each thing is is NOT enough. Definitely first focus on understanding the basics, and be efficient at the geometric optics portion with the mirrors and lens. But, there's a ton of application and optical phenomena for each item that you have to know and understand. I'll list some things I remember later on.

-For the laser shoot, practice practice and practice. While building a laser shoot surface is probably unrealistic for the purpose of saving money, attach sheets of paper together, measure dimensions for the surface, draw the line in the middle, and most importantly, have the walls on the side - they can make it really hard to angle the mirrors and if you don't take them into account, you'll make more mistakes and waste time trying to turn the mirrors with the wall in the way.

Also CREATE A TEMPLATE(s) for different circumstances to save time and reduce the pretty big potential for error that the laser shoot has. 2011, we didn't even consider making one and failed both we tried it. 2012, we made one (though we could just make 4 45-degree angles for the mirrors so it was easier) and it worked nicely. Essentially we made a "u" with three strips of paper (using the red lines cut out from lined paper - don't risk drawing the lines yourself) with two protractors (45 degree angles marked) at the two bottom corners. The other two protractors we essentially lined them up with the line in the middle of the LSS during the competition depending on where the barriers were.

=States Level:=

-Expect an extremely long test (2011 test: was like 8-9 pages of short answer questions, 2012: like 30 multiple choice, 15 short answers, and 5-8 longer (1 part) problems). So make sure to know your binder inside-out, where pages are, and work fast.

-Expect some mini-lab stations in addition to the LSS. This includes identifying parts of an eye in a fake model, identifying and answer questions about microscope (probably other ones too), a station that either is essentially like the double slit experiment or one that requires you to move stuff to focus light and find the focal length of a lens.

Questions I remember: In addition to what's emphasized in the basics (make sure you get these down first!):

Know types of aberrations. Understand diffraction well - the binder definitely lacks some information on this and there was a question that you have to understand construction and interference that asked about where the radio signal is the strongest for two radio towers. Know mirages (refraction), fiber optics (critical angle of refraction), morpho butterfly wings (blue wings on top and brown on bottom due to dispersion), and how rainbows form (sun behind you with 42 degrees). For lens-maker's equation, know the extended version (that has n1/n2 and the (n-1)d/nr1r2 term and how they work) - there was a proof using it. Know specifics about the eye such as near point distance, myopia, etc and then have the specific parts of the eye in the binder. Know about films (oil, etc) and the math behind how they reflect/refract different colors of light depending on the thickness of the flim. Know where the formula for magnification of a telescope is in the binder.

=Nationals Level:=

-Tests from my experience are shorter and you'll have time to double check your partner and relax a little. Don't get tricked by some questions though: here's a question from 2011 Nationals:

Light with a frequency of 7.5 x 10^14 Hz is traveling through water. What is its wavelength? Solution is at the bottom of the page.

Questions I remember:

-2011 Nationals Test in on the test exchange

-2012:

Lots of questions about how lasers work - most of this is in the binder - includes: optical pumping, optimal length of time of the metastable stages, and calculating the amount of energy in different levels.

Optical illusion called the Moon illusion.

Give show descriptions on diffraction, refraction, etc.

Simple formula for deviation angle and minimum angle of deviation that's in the binder.

Answer: Frequency * wavelength = speed of light, but don't forget that the speed of light is less than 3*10^8 in water (n = c/v definition of index of refraction).