Optics B/C

[Froggie]

Hi all,

This is my first year doing Optics, and I'm not really sure on how the Event Supervisors will be running the event (I have NJ regionals @ UCC in less than 2 weeks). More specifically, I'm wondering -- based on your guys' experience -- how long/hard the tests are for Division B, and the topics that will be assessed. I know that the content assessed should align with the guidelines in the rules packet, but based on my limited experience, some of the material covered in tests are way harder than what I studied for (like some of the tests on the Test Exchange), while some tests are extremely easy. Moreover, how will the Event Supervisors be running the LSS? For example, how much time do we have to make calculations/place our mirrors down? I know that the rules state that "Participants must make all measurements ... within a 4-minute time period.", but in previous years, have Event Supervisors tweaked the time limit/constraints for the LSS setup?


-- jxxu20

The rules stating the topics can be bended a lot, because they are very broad. I think it's best to have as much info as you can in your binder.

Last year, we used 5 mirrors and no barrier mirror. Some ESs (?) might have 2 or 3 LSSs (?) so that they can get through the teams quicker (I think the most I've seen is 3). I've never had ESs change the 4-minute limit, and I highly doubt they would.

[jxxu20]

Cool, thanks!

One more question (sorry for so many questions!): do the rules specify the width of the wooden blocks which the mirrors will be placed on, or is this up to the Supervisor's discretion?

[Unome]

Cool, thanks!

One more question (sorry for so many questions!): do the rules specify the width of the wooden blocks which the mirrors will be placed on, or is this up to the Supervisor's discretion?

This is described in rules 3.d and 3.h.

[jxxu20]

Another question (again, I'm really sorry for bothering you guys with so many questions!!!): the rules state that we're not allowed to directly mark the LSS. However, are we allowed to put a template on the LSS and mark the template (not the LSS itself)?

[kenniky]

Another question (again, I'm really sorry for bothering you guys with so many questions!!!): the rules state that we're not allowed to directly mark the LSS. However, are we allowed to put a template on the LSS and mark the template (not the LSS itself)?

As long as you don't do any permanent damage to the LSS it's fine. Weak tape is probably allowed as well, for example

[jxxu20]

One more...question...ok guys I know this is getting very annoying but I just want to know

For Division B, do we need to know about minimum deviation and deviation angle for prisms, and do we need to know about constructive/destructive/double-slit interference, and calculations for each? I'm taking the 2012 Battle of Valley Forge Division C Optics test (on the test exchange) and some other Division C tests as practice (I ran out of Div. B tests to take) and am wondering if Division B should know about those topics. I have somewhat of an understanding about minimum deviation/interference, but it would really help if someone could explain these topics to me in detail, and provide an answer as to whether Division B peeps will be assessed on this. Also, should we know about electron transitions? (I'm assuming maybe as the rules describe that we should know about absorption/emission spectra, and electron transitions relate to this.)

And finally...these two questions:
a. In 1987, a supernova was observed in the Large Magellanic Cloud, a nearby dwarf galaxy. This supernova is estimated to be 1.76*10^21 m from Earth. How many years prior to our observation of it did the explosion actually occur?
b. Earth is 2.5 times from the sun than is Mercury. How much brighter does the sun appear on the surface of Mercury compared to the surface of the Earth?

I think these require using the Doppler Shift equations, but I'm still stuck. Could you guys explain how to solve problems like these?

Thank you guys for all your help! I appreciate it!

[Unome]

And finally...these two questions:
a. In 1987, a supernova was observed in the Large Magellanic Cloud, a nearby dwarf galaxy. This supernova is estimated to be 1.76*10^21 m from Earth. How many years prior to our observation of it did the explosion actually occur?
b. Earth is 2.5 times from the sun than is Mercury. How much brighter does the sun appear on the surface of Mercury compared to the surface of the Earth?

I think these require using the Doppler Shift equations, but I'm still stuck. Could you guys explain how to solve problems like these?

Thank you guys for all your help! I appreciate it!

For those two questions,

a. The speed of light in a vacuum is approximately 3*10^8 meters per second. Use this to calculate the time in seconds, and convert to years.
b. 2.5 squared - explanation

[jxxu20]

Thanks!

[Pettywap]

How is a ray diagram drawn with two convex lenses?

[Adi1008]

How is a ray diagram drawn with two convex lenses?

Draw the ray diagram for the first convex lens as you would normally. Use the image from the first ray diagram as the object for the second ray diagram.