Lens Definition and 787 Threads

Homework Statement Hi all. This is a problem from one of the problem sheets from earlier in the term. I'm just revising for my exam tomorrow and can't solve this one. Here it is: Consider a light source placed at a fixed distance L from a screen, such that a lens of focal length f can be...

Hello everyone, A friend of mine came up with this question in class and I really do not have a good answer. Suppose you have a convex lens that has been cut in half horizontally and the top half removed. The question is: Will the bottom half of the lens still form an image? I really...

Homework Statement When an object is placed 69.0cm from a certain converging lens, it forms a real image. When the object is moved to 39.0cm from the lens, the image moves 19.0cm farther from the lens. Find the focal length of this lens. Homework Equations 1/do + 1/di = 1/fThe Attempt at a...

Homework Statement A real object is placed 9.00 cm from a converging lens that has a focal length of 24.0 cm. The image is________. My classmate answered "14.4 cm from the lens, virtual, and enlarged," but apparently this is incorrect. I solved it out and chose the option "14.4 cm from the...

Homework Statement A biology student wishes to examine a bug at a magnificaiton of +5.00 by looking through a single lens. the student wants the image of the bug to be a distance of 25cm from the lens. what is the focal length of the lens? Answer:+6.25cm Homework Equations...

I'm looking at concentrating light (e.g. sunlight) with a lens, and trying to figure out the maximum concentration I can get. If you have a perfectly collimated source, a lens can focus that light down to a point, but when the source has some divergence, the point you can focus down to will have...

Hi, I'm using an aspheric lens with a LED light source for a DIY projector. As I understand it, if I place the led light source at the focal length of the aspheric lens, the light should be collimated(parallel) coming out the other side. As I decrease the distance between the led and the...

Homework Statement A lens is designed to work in the visible, near-infrared, and near-ultraviolet. The best resolution of this lens from a diffraction standpoint is Options: a.) the same for all wavelengths. b.) in the near-ultraviolet. c.) indeterminate. d.) in the near-infrared. e.)...

Homework Statement 1. An object is placed 1.5m in front of a convex lens of focal length 500mm. Find the position of the image formed and state its nature. 2. A second convex lens of focal length 25mm is placed 770mm behind the first convex lens. Find the position of the final image formed and...

Hi Guys, I have a question about a telecentric lens I've been studying and was wondering if you guys could help clear some cobwebs in my head. For starters, I am simplifying the TC lens as a compound lens. Also, this lens has 2 degrees of freedom: (1) it can be extended and retracted (2) it...

Hi All, I need help determining focal length value in a two lens system. In the set up, the light source (object) is within a tube, a medium surrounds it with refractive index n1=1.52. The end of the tube is met with a curved convergent surface, the center of which is 0.635 cm away and focal...

Homework Statement An object is placed 400 mm in front of a convex lens of focal length 80 mm. Find the position of the image formed. State the nature of this image. A second concave lens of focal length 25 mm is placed 80 mm behind the first convex lens. Find the position of the final...

Homework Statement For my high school physics coursework I must investigate factors affecting the focal length of a lens. I have focused on radii of curvature and completed my data collection and verified the accuracy using the lens makers equation. However, in the conclusion I am really...

Homework Statement A +15 cm focal length lens and a flat mirror are 45 cm apart (the mirror is to the right of the lens and can be treated as a concave mirror with an infinite focus length). There is an intermediate image 30 cm to the right of the lens (15 cm to the left of the mirror) with...

I was just wondering if a person wearing convex lenses looks at a light source... Will excess heat be generated in his eyes? As it is a converging lens.. Thanks!

Homework Statement My physics coursework hypothesis: "As the thickness of the lens increases, the focal length decreases". I tested this using a ray box, a stand to hold lenses and a screen to see where the light is most focused, which is then measured with a metre ruler. The distance 'u'...

Homework Statement An object is placed 2.4m from a screen, and a lens of focal length f is placed between the object and the screen so that a real image of the object is formed on the screen. When the lens is moved 1.2m toward the screen, another real image of the object is formed on the...

I googled for lens formula's proof on the internet and found one here http://www.tutorvista.com/content/physics/physics-ii/light-refraction/convex-lens-formula.php The problem is that during the course of derivation, it is assumed that image distance is -u following the sign convention...

Hello. I'm looking for a lens that can collimate (or focus far away >500mm ) a light coming out from a LED. before I give more details is this even possible? Thanks.

Dear All, I need you kind support in a problem, which I am unable to figure out. It is regarding thick lens. I am determining lens principal planes and radius using shaping factor and focal length. The forward problem I am using is, Focal length 1/f = (n-1)*[1/r1 - 1/r2...

lens -- What physical features makes a lens thin? What physical features makes a lens thin? How can you differentiate one lens from the other based on their thickness? What is the measure of their thickness?

Optics -- magnification of a converging lens Homework Statement Dioptry of converging lens is $D=3$. What is magnification ##u##? Homework Equations The Attempt at a Solution ##\frac{1}{f}=D## - dioptry. \frac{1}{f}=\frac{1}{p}+\frac{1}{l} u=\frac{l}{p} l=up...

Homework Statement A convex mirror with a focal length of -20 cm is 18 cm from a convex lens whose focal length is 6.0 cm. An object is located between them, 10 cm from the mirror and 8.0 cm from the lens. The object will produce two images, one from the light which just goes through the...

So we are learning the lens formula and I have two textbooks, my school textbook and another one that is much more detailed. My school textbook gives the lens formula as:- 1/f=1/v-1/u while the other one gives 1/f=1/v+1/u (v is image distance and u is object distance) There both different! I...

Homework Statement General question here: If I have a lens that looks like two concave lenses put together (I believe it is called a Meniscus), how do I conceptually tell whether the lens should be converging or diverging? I think I remember reading something saying that it depends upon which...

Homework Statement Trying to find the number of diffraction maxima and the width of the whole pattern. \lambda = 500nm b = 2.8μm (Slit Width) f = 100mm r = 25mm L = 25mm (Slit to Lens) Homework Equations I have the worked out the irradiance formula as: I(\theta)=I_0...

I'd like to know why a ray of light passing through the optical center of a convex lens does not get refracted at all. According to my knowledge, a ray of light will not get refracted if the angle of incidence is zero i.e. it is along the normal. With this in mind, I see how a ray traveling...

optics, the resulting power of the lens...?? a thin lens , made of refractive index 1.5,has a front surface +11 d power and back surface -6d ..if this lens is submerged in a liquid of refractive index 1.6, the resulting power of the lens is... a)-1 dioptre b)+1 dioptre c)-5 dioptre...

Any help much appreciated - this is driving me crazy! Homework Statement Show that the focal length of a half ball lens, in air, (in the paraxial limit) is given by: f=R/n-1 Homework Equations Equation (from Hecht- Optics), for refraction at a spherical interface: nm/s0 + nl/s1...

Homework Statement A certain lens focuses light from an object 2.90m away as an image 46.9cm on the other side of the lens. 1. What type of lens is it? (Converging or Diverging?) 2. What is the focal length? 3. Is the image real or virtual? Homework Equations 1/di + 1/do = 1/f...

Homework Statement Parallel rays of green mercury light with a wavelength of 546 nm pass through a slit covering a lens with a focal length of 60.0 cm. In the focal plane of the lens the distance from the central maximum to the first minimum is 10.2 mm. What is the width of the slit...

Homework Statement You have paid big bucks to see The Bourne Legacy at the 3-D IMAX theater in Vancouver. Just before the movie is about to begin, the theater staff tell you that the lens for the projector has just broken! You really want to see the movie and decide that it should be simple to...

Homework Statement A 2.0--tall candle flame is 2.1 m from a wall. You happen to have a lens with a focal length of 37 cm . How many places can you put the lens to form a well-focused image of the candle flame on the wall? For each location, what are the height and orientation of the...

I was solving the following problem, and I've got confused at the second question http://img407.imageshack.us/img407/7921/43545856.png 1) An object is put at the center of curvature C of a convergent lens. Where is the image? Calculate by gauss equation. It's obvious that the image is in...

The question can be found here: http://gyazo.com/fc4d26cd35e6ce368ad2a8ed504f1dcc The refractive index it references can be found here: http://gyazo.com/94fd2f3b5ea7da9226c3acd56b0024c1 I'm not really sure where to get started on the "showing" part of the question. I anticipate that Snell's...

Homework Statement A converging lens with a focal length of 14.2 cm is used to inspect a coin. The lens forms a virtual image 30.1 cm away. What is the magnification? Homework Equations (1/Si) + (1/So) = (1/f) M = (hi/ho) = (-Si/So) The Attempt at a Solution 1/So = 1/f - 1/Si...

The cartesian sign convention for a convex lens is follows: 1. All distances on the principal axis are measured from the optical center. 2. The distances measured in the direction of incident rays are positive and all the distances measured in the direction opposite to that of the incident...

Hi, I'm Chaitanya, 4th year undergraduate student in biomedical engg. I have an idea of making a mobile phone application which measures the power of your spectacle glasses. The idea is we take an image with the phone's inbuilt camera. One of the spectacle lens will be held in front of the...

http://www.sciencedaily.com/releases/2012/08/120824093523.htm If I understand the technology correctly these optical antennas substitute surface plasmon effects for the phase delays of the light passing through glass. They also use standard semiconductor manufacturing techniques meaning mass...

Hi friends, I've a very simple doubt. The lens maker equation, why is it called lens maker equation? What is the reason behind that? thank you in advance.

My question is as follows: Does the focal length of a concave lens change when put into a medium such as water? Initially the focal length of the lens is 20 cm in air. Would it get larger or small in water?

Cylindrical lenses focus light rays onto a line instead of a point. Is that means several images will be formed from a point object aftering passing through the lens? (please see the attached files 1 and 2) If I am correct, can anyone explain to me,when you add water to a tall water...

Homework Statement A projection aligner has an object to lens distance of 500mm. Calculate lens diameter for the aligner if NA = 0.28. Assume the usable area of lens is 90% of its diameter.Homework Equations NA = r / D Note: NA is the numerical aperture. The Attempt at a Solution I know that...

Hello. I need some sort of explanation. I was unsuccessfully trying to find information on the web and derivation by hand seems rather complicated for me. So I have a such set-up: HeNe laser ->> plano-concave lense )], light is incident by some angle (NON 0°). then looking to reflection...

images in a diverging lens are always virtual. when an objectis placed betweenthe focus and optical centre of a converging lens, the image is also virtual. what are the differences between these virtual images? explain by studying the 4 characteristics of each image. i have no idea of...

Homework Statement Its not a specific question but a general one to solve similar questions. I need to find focal length of a lens silvered at one face Homework Equations The Attempt at a Solution I know a convex lens silvered at one face will behave as an effective concave lens...

I have this in my home work and i am not 100% on if i have it right or not A converging lens with a focal length of 25 cm is used to make a slide projector. If the image is to be projected onto a screen 10m away, how far should the lens be located from the transparency? I did it like...

Homework Statement I am studying for my final and just want some clarification on mirror facts. Homework Equations The Attempt at a Solution Convex: focal length = negative and concave is opposite positive Diverginging = - image dist converging just the opposite or positive if...

Homework Statement A compound microscope consists of two converging lenses. Lens 1, called the objective, is a distance 61.0 mm from lens 2, called the eyepiece. The objective is placed in between the object and the eyepiece. The objective has a focal length of 15.0 mm, and the eyepiece has...

is it true when we use concave lens, we can obtain focal length when we get the sharp image.. is it possible to get more than one sharp image when we change the object distance (distance between object and lens)