Focus Definition and 200 Threads

Hello. I've read in many books that the orbits of the planets of our Solar system are ellipses. With the one Focus as the Sun. Well, what is the other one? I mean every ellipse has two focuses...

I have my BA in physics and two years of graduate work at Auburn. I had an excellent experience there as a TA, but my own courses suffered. Quite a bit of my time was spent messing around in the intro lab. I am currently accepted at University of Alabama Huntsville to start up with their...

When I curl my hand up and look through it, even though I have terrible eye sight I can read the title of a book on my shelf even though I can't if I'm not wearing my glasses. Why is this? I just had a lecture on SNOM, (Scanning Nearfield Optical Microscope), where the lecturer made a comparison...

Homework Statement Write the equation of the parabola described. Vertex: (2, 4) Focus: (2,6) Homework Equations (x-h)^2 = 4p(y-k) The Attempt at a Solution (x-2)^2 = 4(2)(y-4) x^2-4x+4 = 8y -32 Do I need to isolate one of the variables, or can I leave the equation like this?

It fell halfway over, denting my metal garbage can lid. The finderscope came off but I could easily reattach it. I can see light and blur now...what should I do?? I don't want to just open it up without knowing what I'm looking for. Thank you!

Prove how focus of a spherical mirror = Radius of curvature/2

Lens can focus the light to a smaller spot by ...?? I learn that increase of the beam size of the laser before coupling it to the fiber can increase the coupling efficiency of it. Can I know why is this so? Maybe the fiber is of very small diameter, and the focal lens in front of the...

Are you interested in earning $100 to share your opinions? We're looking for Chemical Engineers, age 22- 35 to participate in a 1 1/2 hour discussion. We will be hosting focus groups in Houston, Chicago, and Philadelphia, and we need members of AIChE as well as non-members. The...

I'm currently applying to a few reu's and all of them ask for a personnel statement. Most ask for a statement of purpose (why i want to go to an reu) and my goals for the future. My question is what is exactly i should concentrate on. Should I concentrate on why i want to go reu's in general...

Hello, Iam self-studying pre-calculus, I just wanted to know what topics should I be focusing on in Pre-Calculus so ican move on to and be fully prepared for Calculus that's all and thank you, MoePhysics

An ellipse is a conic section. If you construct an ellipse using a cone, does the axis of the cone cross through one of the foci of the ellipse? if so, how can this be shown mathematically? This is just purely out of curiosity.

Homework Statement find the focus and directrix of the parabola: (y+2)^2 = 16(x-1) Homework Equations (y-k)^2= 4a(x-h) focus: ( h+a,k) vertex: (h,k) The Attempt at a Solution k=-2,h=1,a=16/4=4!, vertex at (1,-2) focus ( 5,-2) does that mean that i solved the problem or do...

An object is placed 1m in front of a plane mirror. An observer stands 3m behind the object. For what distance must the observer focus his eyes in order to see the image of the object?

How do I calculate the estimated power of a motor needed for a ford focus, engine size:1788cc, 4 cylinders??

After I discovered that someone had made a handheld tesla coil (http://www.rmcybernetics.com/projects/DIY_Devices/plasma-gun.htm), I started thinking about the possibilities. For example, would it be possible to use a magnetic field(s) to control and focus the energy that is being randomly...

I was discovering a way to focus a number of charged particles which has been accelerated by Van de Graff generator into a beam.I do tried to find ideas in uniform magnetic field,but it seems I can only focus the particles onto a point rather than a beam.So here I was asking whether there had...

Hi First i should apologies if this should have been posted in the homework sections but the three points that are automatically added to the post before writting doesn't really fit my question, so i decided to post it here. Then a little info about the situation might be in order. I'm...

Homework Statement A microscope has a converging lens (eyepiece) with focal length of 2.50 cm mounted on one end of a tube of adjustable length. At the other end is another converging lens (objective) with a focal length of 1.00 cm. When you place the sample 1.30 cm from the objective, what...

Hi all. This question has probably been asked before but I couldn't find it so. Over the past year I have dabbled with a few programming languages such as C,C++ and perl. My question is, which one should I really focus on and why? Thanks for any help.

Assuming ray optics model is valid, what lens profile focuses light to a point? It must not be spherical, otherwise there would not be the term 'spherical abberation'.

I am a second-year student and I go to a school with a not-so-strong theoretical physics department but a very strong math department. I am planning on going to grad school in theoretical physics. I will have completed the physics major at the end of this semester and I am deciding which...

Internship: Focus on Electrical or Systems Engineerin? Hi, I'm a junior EE major. I've had an internship last summer as a manufacturing engineering intern and I'll have one more summer left (between my Jr and Sr year) until I graduate. When finding internships for this summer, should I solely...

I've just been sitting here at my desk for the last three hours, and I realized that I have gotten about 1/2 hour worth of work done. I just keep getting distracted by things. Do any of you have any good techniques for focusing on things (assignments/studying/research) for long periods of...

Am I making this out to be too simple? I am given: The Sun's center is at one focus of Earth's orbit, how far from this focus is the other focus in meters and in terms of the solar radius? eccentricity=.0167 semimajor axis=a=1.5*10^11 meters. solar radius=R=6.96 *10^8 meters Now if c is the...

Primary focus magnification? Hello all: My name is Miguel, from Buenos Aires. I have a question... is it right in formal optics to name "magnification" the below formula or "focal distance equivalent" of a camera attached in primary focus (without telescope ocular and camera objetive, of...

How do you find the value of the distance between the focus and vertix for the parabola given by the equation 6x^2 + 8 = 2y.

Well, I'm new in town and I have a serious problem. Read the story and then tell me if its possible: In a open spot of a forest, a kid sees a sparkle from a 150 meters Manson's window. The house is located 5 meters above the forest floor level and the open spot 1-2 meters from the floor...

I am a junior in electrical engineering, and I'm at the point where I need to start choosing my technical electives (my focus courses). I took my first Electrodynamics course this semester. I friggen' loved the material. I thought it was VERY interesting although quite hard. I'm thinking about...

where is the principle focus of a plain mirror?

Has anyone here ever taken adderall in order to study better or focus more on a test?

From using a magnifying lens under the Sun, I gather it can focus all or most of the light impinging on its surface area to a small spot and that is how it is able to create a greater intensity light at its focus (disregarding absorption in the lens.) Correct? What portion of the total light...

I just changed my major to EE (actually last semester). I was previously a comp sci major. While in CS I took calc I, II, discrete math, then calc III and linear algebra. I hated math when I took up to discrete math. I always just wanted to solve the problems on the computer. It wasn't until...

Find the vertex, focus, and the directrix of the parabola. I get tripped up sometimes, but I know how to find all of the stuff with an equation like this : (x+1)^2 +8(y+3) = 0 But how do I find it with equations like this y^2=-6x or x+y^2=0 Can you complete the square with...

is it possible to focus an axial ray through a double plano piece of glass placed in air? i don't think so because the glass will not reflect the ray towards the optical axis for the ray to focus in. is this thinking correct?

In school physics i have learned that the focus for a circular convex(converging) lens is f=r/2 where r is the radius and f is focus. But wouldn't a pair of identical lens made of a different material eg glass and perspecs which have different refractive indexes have different point of focus?

Since I got interested enough in Neanderthal man to start reading about him, and because this leads to questions about whether or not modern man could have bred with Neanderthal, I have found myself getting into the habit of constantly checking out the slope of the foreheads of every person I...

Fins an equation for the parabola with focus at (-5,0) and vertex at (-5,-4). I have come up with: x^2 + 10x + 16y + 89 = 0 How far off am I?

vertex (-2, 3), focus (0,3) Find the equation of the parabola. Dirac.

Could someone please give me a rough estimate as to what the mass of a 20MW focus fusion reactor might be, please. Seamo

Hi! I am having trouble with this question: You are trying to photograph a bird sitting on a tree branch, but a tall hedge is blocking your view. However, as the drawing shows, a plane mirror reflects light from the bird into your camera. If x = 4.3 m and y = 4.5 m in the drawing, for what...

So i have a midterm tomorrow in E&M and I'm not well prepared at all. The whole class is pretty much already prepared to fail... so I'm not alone in that at least. Basically, i have one more day (tomorrow) to study, so i best make the best of it. We get to bring index card "cheat sheets" that...

Hi, I need to determine the equation of a parabola given the focus (2,3) and the directrix y=-1 I sketched out a parabola opening up wards with a vertex of (1,1) I made two distance equations one for any point on the parabola to the focus, and one distance from the directrix to any point...

Find the equation of ellipse given vertices and focus Check please Hi the question is find the equation of the following ellipse, given vertices at (8,3) and (-4,3) and one focus at (6,3) Well I drew a digram with the 3 points First I found the midpoint of the given vertices to get the...

I found this. Is it cranks or for real? http://www.progressiveengineer.com/PEWebBackissues2002/PEWeb%2028%20Jul%2002-2/28editor.htm http://www.focusfusion.org/

Hello, Not to belong: i was good at school, and focussing on classes wad not a question for me, i was not studying too much every day, but i was able to focus many hours on studying on the exams night... The Problem is i lived in the middle east for the most in my life, and since i was...

or getting it. I am but I'll be damned if I let it destroy my focus on school. In part that's probably why Halo 2 and Chessmaster are the only games I will be playing the rest of this year and far into 2k5 maybe. Sad really when a video game is threatening to take my focus. What happened to...

hello, i am not sure that this is the correct forum to post in, but i am confident that the moderators can swiftly correct my error if that is the case. I was wondering a little about cameras and their auto foucs. How does it work and what is the math behind it?

http://www.nature.com/news/2004/040719/full/040719-19.html

what is the definiton of focus?if i put a converging lens or diverging lens in water,will the focus change? do you guys have msn? i have one.

how can we find the focus ?thanks