Scioly.org

bchero wrote:So the textbook for a survey course in Optics is good enough?

:shrug: Does it have all the info under the rules? If yes, then yes. If no, then no.

paleonaps wrote:Oh. Okay then.
Although I'm sure there are a few video games dealing with optics. It would be pretty easy to make, I think.

Flash Focus, for the DS

I've been searching online a lot for practice tests, but I can't seem to find many. Actually, there are a lot, but they're either too easy or sort of redundant. Anyone have a good source (for division C)?

iFlare wrote:I've been searching online a lot for practice tests, but I can't seem to find many. Actually, there are a lot, but they're either too easy or sort of redundant. Anyone have a good source (for division C)?

Have you tried the one in the test exchange?

amerikestrel wrote:

iFlare wrote:I've been searching online a lot for practice tests, but I can't seem to find many. Actually, there are a lot, but they're either too easy or sort of redundant. Anyone have a good source (for division C)?

Have you tried the one in the test exchange?

I have, actually. I thought it was good, but a little easy. If I remember correctly, it was a Division B test with some extra problems, yes?

iFlare wrote:

amerikestrel wrote:

iFlare wrote:I've been searching online a lot for practice tests, but I can't seem to find many. Actually, there are a lot, but they're either too easy or sort of redundant. Anyone have a good source (for division C)?

Have you tried the one in the test exchange?

I have, actually. I thought it was good, but a little easy. If I remember correctly, it was a Division B test with some extra problems, yes?

Unfortunately you won't find many competition tests, because optics has only been a trial event. You might try looking for general optics tests and quizzes online (say, from optics/physics courses), and hopefully there will be more tests available when invitationals start.

So yesterday was the first Invites of the year, and I was less prepared than I thought for this event. I understood all the questions, I just didn't have all the formulas written down that I needed. However I did come across a question that confused me. It went something like this:

question wrote:You have two thin lenses pressed together, each with a radii curvature of 30cm and a refractive index of 1.5 What is the combined focal distance?

So the first thing I thought was the formula for combined focal distance, but first I needed to know the individual focal distance for each lens. I know this, but I need to know both the curvature for the outer most side of the lens as well as the innermost, and I know that both can't be 30 because then I would have division by zero. How do you find the other side of the lens' curvature?

brobo wrote:So yesterday was the first Invites of the year, and I was less prepared than I thought for this event. I understood all the questions, I just didn't have all the formulas written down that I needed. However I did come across a question that confused me. It went something like this:

question wrote:You have two thin lenses pressed together, each with a radii curvature of 30cm and a refractive index of 1.5 What is the combined focal distance?

So the first thing I thought was the formula for combined focal distance, but first I needed to know the individual focal distance for each lens. I know this, but I need to know both the curvature for the outer most side of the lens as well as the innermost, and I know that both can't be 30 because then I would have division by zero. How do you find the other side of the lens' curvature?

Did it tell you whether they were concave or convex?

ichaelm wrote:

brobo wrote:So yesterday was the first Invites of the year, and I was less prepared than I thought for this event. I understood all the questions, I just didn't have all the formulas written down that I needed. However I did come across a question that confused me. It went something like this:

question wrote:You have two thin lenses pressed together, each with a radii curvature of 30cm and a refractive index of 1.5 What is the combined focal distance?

So the first thing I thought was the formula for combined focal distance, but first I needed to know the individual focal distance for each lens. I know this, but I need to know both the curvature for the outer most side of the lens as well as the innermost, and I know that both can't be 30 because then I would have division by zero. How do you find the other side of the lens' curvature?

Did it tell you whether they were concave or convex?

Yes, I just don't remember which one it was.

brobo wrote:

ichaelm wrote:Did it tell you whether they were concave or convex?

Yes, I just don't remember which one it was.

Well, if they were both double convex (for example), then you have to say that for each lens, one of the radii is forwards and the other is backwards. Different versions of the thin lens approximation equation will have different sign conventions. Usually, though, positive is away from you, and negative is towards you. In that case, one of the radii would be 30 cm, and the other would be -30 cm.