Lens Definition and 787 Threads

The actual frame size of "35-mm" film is 24 mm x 36 mm. You want to take a photograph of your friend, who is 1.70 m tall. Your camera has a 60.0 mm focal length lens. How far from the camera should your friend stand in order to produce a 36.0 mm-tall image on the film? i thought you would...

The given problem: What is the focal length of a Plano-convex lens, assuming parallel rays of light from s=∞ is traveling from the flat end of the lens. The lens is a glass hemisphere of radius R. Additionally the index of refraction of glass is higher than that of air. Homework...

Homework Statement The human eyeball is approximately spherical with a diameter of around 25mm. At the back of the eye is the retina, while at the front is a compound lens comprising the cornea (of fixed focal length) and the lens itself (with variable focal length), which can be...

Homework Statement Under what conditions will a thin converging lens form: a) a real image, b) an inverted image, and c) an image smaller than the object? Homework Equations none The Attempt at a Solution I have concluded that: a) the object needs to be outside the focal...

Homework Statement For each thin lens shown in the figure , calculate the location of the image of an object that is 18.5 {\rm cm} to the left of the lens. The lens material has a refractive index of 1.50, and the radii of curvature shown are only the magnitudes...

Homework Statement You are standing in front of a lens that projects an image of you onto a wall 2.80 {\rm m} on the other side of the lens. This image is three times your height. How far are you from the lens? Is your image erect or inverted? What is the focal length of the lens? Is the...

Homework Statement If the focal length of the concave lens is -7.50 cm, at what distance d_o from the lens should an object be placed so that its image is formed 3.70 cm from the lens? What is the magnification m produced by the concave lens described in above? Where should the object be...

Homework Statement A converging lens ( f = 10.4 cm) is held 8.80 cm in front of a newspaper, the print size of which has a height of 2.04 mm. Find the image distance (in cm) and the height (in mm) of the magnified print. D= _____cm H= _____cm Homework Equations 1/f=1/do+1/di...

Hi guys I wonder if you can explain this to me. In http://en.wikipedia.org/wiki/Ray_transfer_matrix_analysis#Table_of_ray_transfer_matrices it says under "Thin lens" that the ray matrix is given by \left( {\begin{array}{*{20}c} {r_{final} } \\ {r_{final}^' } \\ \end{array}} \right) =...

So, I've been wondering. Anyone know what shape/prescription a contact lens would have to be in order for an eye to be able to focus on something 1mm away (assuming the distance of focus in the eye is around 4 cm)? Does it have to do with focal length of the lens?

I am wondering... say an object was put directly on a lens and you wanted the projected image to focus at around 3 cm on the other side. How do you determine how wide the lens has to be? (please see attachment)

Came across it when I was studying about Cathode ray oscilloscopes, it says that two sets of parallel plates are kept at a high pd with another one of relatively lower pd between them. Then electrons from an electron gun are shot into it. It says that the electrons are focused on the cro's...

Homework Statement An object is 1.75 m to the left of a lens of focal length 0.62 m. A second lens of focal length -2.7 m is 0.52 m to the right of the first lens. Find the distance between the object and the final image formed by the second lens. Homework Equations (1/x1)+(1/image)=...

Hello all! Again I am a lost molecular biologist in the realm of physics, but this question shouldn't be so difficult! We are using an Olympus microscope to take pictures of our live cultures here in the lab and we have a real REAL old nikon attached to it to take pictures. I want to be...

Hello, Can someone update me about the success of gravity probe 2 please? Narasimha!

The diagram below is not to scale. I'm trying to add a lens (or lenses) behind the one shown in this camera so that I can focus the image on a film plane of 15mm, rather than the current 120mm (Y). The focal length (X) needs to be at or greater than the current 60mm. What would the...

[b]1. A 70 mm focal-length lens is used to focus an image on the film of a camera. The maximum distance allowed between the lens and the film plane is 120 mm. How far ahead of the film should the lens be if the object to be photographed is at the following distance from the lens?When it is 13.2m...

Lens and distances I do use images as help when working theses out. going to try and scan theses in but tryed my best just using pc for now. 0 = lens F = focal length 1) a camera with a 50mm focal length lens is focused on a persons face 1m from the lense. show that the film will be about...

Ok so this really has nothing to do with astronomy, besides the use of lens,... but it is a lens question so here goes :P (moderators may move this if their's a more appropriate place for it) Information printed on the lens: "Carl Zeiss Tessar 2.0/3.7 2MP Autofocus". This is from a...

Homework Statement A simple glass lens do not focus the image of an object correctly under white light because a. the lens absorbs light b. the glass has come colouration due to impurities c. the surface of the lens reflect some light d. a glass prism splits sunlight into different...

1.An object is placed to the left of a lens, and a real image is formed to the right of the lens. The image is inverted relative to the object and is one-half the size of the object. The distance between the object and the image is 102.0 cm. (a1) How far from the lens is the object...

please suggest some good references for lens design. i wish to start from scratch.. i am a complete amateur in this field.

Homework Statement A concave mirror has a focal length of f=50 cm. If an object is at o=500cm, where is the image? Homework Equations 1/f = 1/o + 1/i The Attempt at a Solution 1/50 = 1/500 + 1/55.56 What I don't understand is "where is the image"? How do I interpret it from...

i was asked to find the angle \theta, the height h2, and the back focal length in terms of the radius of curvatures. I'm really stunned that i couldn't draw a line. thanks in advance. http://img94.imageshack.us/img94/8336/lens.png

Homework Statement A small fish, four feet below the surface of Lake Lansing is viewed through a simple thin converging lens with focal length 30 feet. If the lens is 2 feet above the water surface, where is the image of the fish seen by the observer? Assume the fish lies on the optical axis...

Hello all, doing some reasoning and subsequent Gadenkin experiments, followed by a Non-scientific experiment results in some interesting changes in magnetic fields using glass lenses. Here it is, and please help me to explain this phenomenon, as I can find no mention of it anywhere. Two bar...

Recently, I purchased a pair of glasses from a privately owned optic store. I specifically asked for hi-index lens (1.56 or 1.60, I am not sure). The lens I got, however, is kind of thick (around 5 mm thick on the edges).My eye -sight is poor though, -5.00 sphere, -1.25 cylinder on the worst...

Working on some optics problems and I am confused about the front and back of the lens. The sign conventions are key to finding the correct image location. Now, is the front always where the object is located? The problem I am working on involves a divergent lens and a concave mirror. The...

Homework Statement Question B only Homework Equations The Attempt at a Solution 1) Why we use f=15.0cm? Shouldn't it be f=infinity considering plane mirror have an infinity focal length? 2) Normally I do combination(lens, mirrors), firstly I will consider the front...

Photography/optical lens distortion/surveying. Please move to appropriate forum. I wish to survey an area of a friend's backyard using overhead photos. I can get photos from about 25 feet up a TV antenna with a digital SLR that has a 14-42mm lens. The area to be surveyed is 70'x20' and is...

Homework Statement A diverging lens with focus 5 cm is placed on a filament. Find the distance between the lens and the filamentHomework Equations \frac{1}{f}=\frac{1}{di}+\frac{1}{d}The Attempt at a Solution Focus of diverging lens is negative so, f = -5 cm. I think the question is asking...

An object at the focal length distance from the lens is imaged at infinity,Do this mean that under this situation, our eyes could not see the image? but as our eyes could see the stars from infinity, do this mean that the image of lens which is discussed above is just viewed through screen ,and...

Homework Statement The figure illustrates qualitatively a converging lens focusing monochromatic rays from A to B. The vertical and horizontal scales of the figure are not the same. The top ray leaves A at an angle of 2.38 deg above the optic axis and leaves B at an angle of 1.25 deg below the...

Homework Statement What is the minimum thickness of coating which should be placed on a lens in order to minimize reflection of 661 nm light? The index of refraction of the coating material is 1.40 and the index of the glass is 1.65. Hint: You must take into account the 180 degree...

i have a camera with 1/3 " format. I have a cctv lens in front of it with a focal length of 50mm. In order to improve my FOV i intend to use a cctv lens of a smaller focal length, and the vendor is providing me a smaller focal length for a 2/3 " format. i want to know if a cctv of say 25mm...

Homework Statement I'm looking for someone to clarify a strange result regarding angular magnification. For both mirrors and lens. Homework Equations m(angular) = θ'/θ M(lateral) = h'/h = - d'/d θ ≈ h/d (for small angles) The Attempt at a Solution Using the angle equation, I get a...

An object 1.95 cm high is placed 11.2 cm in front of a convex mirror with a radius of curvature of 9.8 cm. Where is the image formed?? So i know Di= (Doxf)/(Do+f)...(11.2 x 9.8)/ (11.2 + 9.8) = 5.23 cm However, the correct answer is 3.41 cm What am i doing wrong here? I know that the...

Homework Statement part1: In the Figure below a lens of focal length 8 cm is placed between a plane mirror and a pin hole. The other side of the pin hole is illuminated by a light source (not shown), so that the light passes through the hole and is then collected by the lens. If the pin hole...

the near point and far point of an eye are 35cm and 300cm respectively.what is power of lens so that the person can see objects at 25cm .with this lens what is the maximum distance he can see. f=xd/x-d p=1/f in m i could only solve the first part of the problem.p=1.14d...

Good afternoon, I want to check another problem about optical physics: There are taken N equal converging lens, ordered one by one in a distance of f, where f is the focal distance. There is an object standing in a distance of 0,5*f of the first lens. A Sketch...

Hi all, I am implementing a lab activity for a 2 lens set-up that will serve as a simple telescope. In the teacher's manual, it lists down 2 plano-convex lenses, with the 2 curved surfaces facing each other. The plane faces will respectively face the light source and the observer's eye...

Hi, I have a fresnel lens from a old big screen tv and it is roughly 1 meter square. The focal point comes down to roughly 2.5cm square (1"). On a sunny day in Hawaii I can melt copper wire after about a minute. Copper has a melting point of 1083°C (1981.4 °F) . That's some serious fun! I...

Homework Statement A student is working in an optics lab and has a light bulb which is 100 cm from a screen. She needs to make a real image a real image of the bulb on the screen and she has a converging lens with a focal length of +15 cm. Find two places she can put the lens and give object...

Homework Statement Diverging lenses produce a "virtual" image, which can be seen but can't be projected, and converging lenses produce a "real" image which can be projected but not seen. How come we can see the image produced by a converging lens, which is supposed to be a real image...

1. When an object 5.0 cm tall is placed 12 cm from a converging lens, an image is formed on the same side of the lens as the object but the image is 61 cm away from the lens. What is the focal length of the lens? 2. 1/f = 1/do + 1/di 3. 1/f = 1/do + 1/di = 1/12 + 1/61...

Lens -- find the focal length 1. An object 3.0 cm tall is placed 20 cm in front of a converging lens. A real image is formed 10 cm from the lens. What is the focal length of the lens? 2. 1/f = 1/do + 1/di 3. 1/f = 1/do + 1/di 1/f = 1/20 + 1/10 f = 6.667 cm...

1. The image of the moon is formed by a concave mirror whose radius of curvature is 4.20 m at a time when the moon's distance is 3.8 x 10^5 km. What is the diameter of the image of the moon if the diameter of the moon is 3480 km? 2. 1/f = 1/do + 1/di M = hi/ho = - di/do 3...

Homework Statement A farsighted woman breaks her current eyeglasses and is using an old pair whose refractive power is 1.655 diopters. Since these eyeglasses do not completely correct her vision, she must hold a newspaper 39.4 cm from her eyes in order to read it. She wears the eyeglasses...

Homework Statement An object is in front of a lens with a focal length of -15cm. An image ½ the side of the object is formed. How far is the object from the lens?Homework Equations m - magnification q - distance from image p - distance from object f - focal length m = -q/p 1/p + 1/q = 1/fThe...