Lenses Definition and 303 Threads

Homework Statement The lens and mirror in the figure below have focal lengths of +74.0 cm and -59.1 cm, respectively. An object is placed 1.00 m to the left of the lens as shown. http://www.jmlproductions.net/jmlproductions/p36-54.gif I need to find the final image location. Homework...

1. A nearsighted person wears contacts with a focal length of -7.6cm. If this person's far point distance with her glasses is 8.7m, what is her uncorrected far point distance? 2. 1/F=1/do+1/di 3. 1/-7.6=1/do+1/870 =-7.534 I am completely lost here...please help. Thanks!

Homework Statement a) In the autocollimation experiment of Sec. 3.5, a thin convex lens is placed 25 cm from a pinhole that acts as a point source of light. A plane mirror placed 20 cm behind the lens reflects the light back through the lens, and the reflected light forms a sharp spot beside...

Heyy this is my first time on here and I'm only doing first year physics so my understanding might not be up to scratch =/ I'm doing a practical on thin lenses where we have to do a various amount of measurements and calculations to do with convex lenses. However I'm not very confident with...

Hi, We have an optical equipment that has a narrow entrance slit, on the other end of the narrow entrance slit two rod lenses are exposed. They are getting dirty for various reasons. Does anybody know of any handheld air/vacuum cleaning with thin nozzle that can penetrate the slit and even...

any idea what these ball lenses are.. ? any specific application?

Homework Statement the question is attached The Attempt at a Solution ok so a and b i can do but c), i donts know whether my answer is right and I am a little confused about the conceptual idea... so first thing i did was found the radius of curvature using the lens maker equ...

A converging lens with f=33.7 cm yields an image with magnification M=−2. Find the object distance. Give your answer ... * in terms of centimeters. Do not include units in your answer. They will be assumed to be cm...

Hi. There's a question that has given some variables which am not sure how to compute to some previous lens/optics equations. These are not the actual variable values by the way. If a projector (square pixel SXGA) has a diagonal size of 5 mm which uses a screen of 1 m in which the distances...

Lenses and optics: solving for focal point. (SOLVED) (2 points, penalty of 0.5) When a flower pot is placed 1.2 meters on the left of a magnifying glass (converging lens), an image is formed on a screen 0.37 meters to the right of the lens. Find the focal length of the lens. Give your answer...

1. A diverging lens with a focal length of -14 cm is placed 12 cm to the right of a converging lens with a focal length of 18 cm. An object is placed 33cm to the left of the converging lens. Where will the final image be located. 2. 1/f = 1/di + 1/do dob = L - dia 3. After solve...

Homework Statement Anne is farsighted; the nearest object she can see clearly without corrective lenses is 2.4 m away. It is 1.8 cm from the lens of her eye to the retina. What should the focal length of her contact lenses be so that she can see clearly objects as close as 24.0 cm from...

Homework Statement Could someone explain to me about the near point and the far point in the eye because I'm confused about the 25 cm for the near point and infinity for the far point. Also, like in problems like this: What eyeglasses would you prescribe for persons with the following...

Homework Statement The focal length of a diverging lens is -20 cm. Locate the object, given that the image is real, erect, and 150% of the size of the object. Homework Equations (1/f)=(1/do)+(1/di) M=-(di/do) The Attempt at a Solution i'm not really sure how a diverging lens forms a...

Hi, I'm new to this place, and I'm not sure if my problem fits with this forum, but I'll give it a try. Right now, I'm building a laser range finder, but my biggest concern will be focusing the reflected laser beam onto a small silicon photodiode. And to add to that, I have barely any...

When I'm given do, ho, and hi. How would i solve for di Normally i would do -di/do = hi/ho and cross-multiply but I'm not sure how the negative comes into effect. do = object distance di = image distance ho = object height hi = image height If... ho = 3cm hi = 4cm do = 5cm...

What if two converging or diverging lenses were placed side by side, in contact with each other. Where would be the image formed for the converging lens, would it be to the right of the lens combined or to the left? Why? Also, where would it be if both lens were diverging? thanks!:)

Path Difference in Lenses... A convex lens will converge all rays parallel to the optical axis to the focus. Now obviously different rays at different distances from the optical axis will travel different distances in reaching the focus. So why does this not create any path difference between...

Why if two concave and convex lenses are nested together, will there be no resulting convergence or divergence if their focal lengths are the same, but if the concave lens has a larger focal length the rays will converge slightly? What is (are) the mathematical equation(s)/reason(s)?

Homework Statement A converging lens has a focal length f, and a diverging lens has a focal length –f, which has the same magnitude as the converging lens. They are separated by a distance D which is greater than f, as shown. Parallel light enters from the left. Will the light be brought...

Homework Statement Heres the problem exactly as written: A system of lenses is composed of three lenses. Calculate the maximum magnification these three lenses will achieve if the lenses are located 35.0 cm apart. The lenses have focal lengths of 15.0, 20.0, and 25.0 cm.Homework Equations 1/p...

I was reading on the f-number of lenses for cameras...somewhere in the text, they stated that the area of the image is proportional to q2, in which q is image distance. I figured the area to be proportional to q, but I don't really see it as q2...so how does this work out?

hello members of www.physicsforums.com ! primarily i want to apologize for the double thread post; i posted another thread at this link: https://www.physicsforums.com/showthread.php?p=1950906#post1950906 and i am afraid it was homework and i did not see the homework section so please forgive...

The statement is that the image formed by the 1st lens acts as the object for the 2nd lens. For 2 thin lenses aligned along a common axis, would this statement be true for when the image formed by the 1st lens is real and past the 2nd lens (while ignoring the effect of the 2nd lens in this...

Homework Statement A simple camera telephoto lens consists of two lenses. The objective lens has a focal length f1 = +36.0 cm. Precisely 33.0 cm behind this lens is a concave lens with a focal length f2 = -10.0 cm. The object to be photographed is 3.67 m in front of the objective lens. (a)...

I was reading on thin lenses, in which the lens makers' equation was proved. The proof first gave the lens (a biconvex lens) a thickness (which it would later consider negligible) so that the light would pass through one surface and out the other (so it comes into contact with 2 surfaces). The...

Homework Statement There are 2 lenses separated by 5 cm. Very far to the left of the first lens is an object (the distance of the object from lens one is NOT given). The focal length of lens 1 is 20 cm and the focal length of lens 2 is 10 cm. Where is the image due to the first lens? State the...

I was reading a bit on thin lenses when a postulation was made that the image formed from the first surface would be the object for the second. The postulation made sense for when the first image is virtual, but I don't see how it works when the first image is real? Can anyone provide me the...

Hello, here is my question: if an object position can only tend to infinity, without ever reaching it (since infinity is just an abstraction), its image will tend to appear on the back focal plane of a converging lens, without ever forming there. The image will always be created on the image...

Homework Statement An object is 18cm in front of a diverging lens that has a focal length of -12cm. How far in front of the lens should the object be placed so that the size of its image is reduced by a factor of 2.0? Homework Equations 1/do + 1/di = 1/f m= -di/do The Attempt at a Solution...

have absolutly no idea where to put this but ill put it here My eyesight is something like +6.25/+6.50 Now the eye man (optomotrist?) said that they only make contact lenses that go up to +6. I was wondering why this is? Also why can't long sighted people have laser eye sugery? Is there...

Homework Statement the figure shows a combination of two identical lenses. There is a 2cm tall object that is 36 cm away from the first lens (f=9 cm). The second lens is 15 cm away from the first lens. It also has a focal length of 9 cm. So, the first question was "find the position of the...

Homework Statement A lens is made of glass for which the refractive index is n[r]=1.5 for red beams and n[v]=1.52 for violet beams. radii of both surfaces are the same and equal R=1m. Find the distance between foci for red and violet beams Homework Equations The Attempt at a Solution

Homework Statement Two lenses, one converging with focal length 20.0cm and one diverging with focal length -10.0cm, are placed 25.cm apart. An object is placed 60.0cm in front of the converging lense. Determine the position of the final image. Homework Equations \frac{1}{s_i} +...

Homework Statement For each of the following object positions in front of a converging lens, suggest at least one practical application. (E.g. overhead projector, camera etc.) a) Between the lens and F' b) At F' c) Between F' and 2F' d) At 2F' e) Beyond 2F' The Attempt at a...

Hi, I need to build a telescope for my physics class. I need to use any 3 lenses(converging or diverging) and 1 mirror. I was thinking of using an achromatic telescope design for that. However I am not sure what kind of lenses to use and whether I should make the eyepiece from two lenses or just...

1. An object is placed in front of a converging lens in such a position that the lens (f = 11.0 cm) creates a real image located 27.0 cm from the lens. Then, with the object remaining in place, the lens is replaced with another converging lens (f = 19.0 cm). A new, real image is formed. What is...

Hi all The expression for the angle deflection on the following page: http://relativity.livingreviews.org/open?pubNo=lrr-1998-12&page=node2.html Is the impact parameter r in the expression the distance to the surface of the objects that deflects the light or the the center of mass of the...

Homework Statement a) A converging lens with a focal length of 15cm has an object 5cm tall placed 40cm to the left of it. To the right, 30 cm away, is a converging lens of focal length 10cm. use the thin lens and magnification formulae to locate the finale image. Find its magnification. b)...

I'm just wondering why PMMA (polymethylmethacrylate) is hydrophobic and does not attract water. I can't find anything that explains this on a molecular level :S

[SOLVED] Contact Lenses Problem Homework Statement A contact lens is made of plastic with an index of refraction of 1.58. The lens has a focal length of +26.0 cm, and its inner surface has a radius of curvature of +20.0 mm. What is the radius of curvature of the outer surface? Homework...

Hey guys, i have two question that me and a couple of my mates couldn't figure out for the life of us in class so i bring them here. The first one at first glance seemed fairly easy Homework Statement Calculate the angle of deviation at a glass air interface for an angle of incidence of...

"To use a graphical approach to determine whether there is a difference between the focal length of a lens when used with red and green light." What would I expect to see? What sort of results do you think I will get? What would be the variable? I need to use the equation 1/u +...

[SOLVED] Lenses - Thin-Lens Equation and Magnification Equation I can't figure out what I am doing wrong, your help would be greatly appreciated :) Here is the Homework Problem A camera is supplied with two interchangeable lenses, whose focal lengths are 35.0 and 150.0 mm. A woman whose...

In a combination of lens experiment we measure U from the mean position b/w two lenses , Why ? If we measure U from the first lens or second lens will there be any difference b/w this case & the above mentioned one ?

Homework Statement I have a final tomorrow, and I there are a couple questions that I don't know. When the angle of incidence is the critical angle, the angle of refraction will be? If a screen is moved 3 times the distance from a light source, what will the intensity on the screen be...

A microscope is made in a tube 25.0 cm long. It magnifies 5.00 x 102 times, 50.0 times by the objective lens and 10.0 times by the eyepiece. What are the focal lengths of the two lenses?

Homework Statement 1)A philatelist uses a magnifying glass with a focal length of 10cm. In order to examine a rare postage stamp, he holds the lens 4 cm from his eyes. If the distance for the most comfortable viewing of the image is 30cm from his eyes, how far from the lens must the postage...

I have a problem in understanding Feynman's derivation of a lens' shape using Fermat's principle. Feynman writes that we have to choose such a surface of the lens that all optical ways from the source S to the focal point F will have the same length (so all will be taken by the traveling light)...

[SOLVED] Understanding CCTV lenses Hey guys, I'm trying to get my head around the way a lens works... I've found the nodal points, and since the medium surrounding the lens is air constant refractive index (air) then they nodal points coincide with the principle planes, right? Also...