Lenses Definition and 303 Threads

The components of a telescope are essentially two convex lenses? Out of curiosity (boredom) I am trying to figure out if the addition of another lens could make the image non-magnified. For instance, what type of lens/other would you add in order to make the image look as if you were...

Hi, I was reading a section which explains about the "thin lens equation for diverging lenses" and it included an example; Formula: 1/f = 1/di + 1/do where f is the focal distance, di is the distance of the image from the center and, do is the distance of the object from the center. Example: f...

Homework Statement You wish to project a slide on a screen. One of the letters on the slide is a p. When you place the slide in the projector, how much the letter look when you insert the slide(as seen from behind the projector)? Explain. a) p b) d c) b d) q Homework Equations How converging...

How is it done? I've done a little research on Wikipedia and found the lensmaker's equation, but one of the values needed to compute focal length is the radius of the lens curvature. Strictly speaking, an aspherical curvature wouldn't have a set radius, would it? The reason I'm asking is because...

Why do very large astronomical telescopes use a mirror rather than a lens for the objective optic?

Which contact lenses do you like the most? For me it's 'Day and Night' although I take it out in the night just to let the eyes breathe better.

Corrective lenses and contact lenses work because of refraction. Do they bend light in a special way that will correct a person's vision for whatever reason it is?

Homework Statement A combination of two thin convex lenses of equal focal lengths,is kept separated along the optic axes by a distance of 20 cm between them.The combination behaves as a lens system of infinite focal length.If an object is kept at 10 cm from the first lens,its image...

Homework Statement Two converging lenses with focal lengths of 40 cm and 20 cm are 10 cm apart. A 2.0-cm-tall object is 60 cm in front of the 40-cm-focal-length converging lens. a. Use ray tracing to find the position and height of the image. do this accurately with a ruler. Determine the...

For this question, assume that the index of refraction of diamond is 2.39, that of glass is 1.65, that of water is 1.30, and that of air is extremely close to 1. A thin lens made of glass has a focal length in air of 16.1 cm. A lens of exactly the same shape is then made from diamond...

A camera with a focal length f of 6 cm is used to take the picture of a person who is 180 cm tall, standing at a distance 3 m in front of the camera. How big will the image of that person be on film? How far behind the lens (assumed to be very thin) must the film be placed? I tried using...

Homework Statement Without her contact lenses, a student can focus an object located 0.80 m to infinity from her eyes. The power lens, measured in diopters, is the reciprocal of the focal length, measured in meters. Assuming that the image distance in the eye is 0.02 m, what lens power does...

Question regarding two lenses in combination - the first is a diverging lens with f = -31.5 cm, and the second is a converging lens, 14 cm away, with f = 20.0 cm. The exact question is 'Where will an object at infinity be focused?' (coming in through the diverging lens), and I kind of understand...

A 1.5-cm tall object is placed 0.50 m to the left of a diverging lens with a focal length of 0.20 m. A converging lens with a focal length of 0.17 m is located 0.08 m to the right of the diverging lens. What is the height and orientation with respect to the original object of the final image...

Homework Statement I'm unable to understand the production of dark fringe in the central point of contact of lens.The text says "the path difference between the rays reflected at the top & bottom of air gap at the point of contact is zero.Actually the ray reflected from the top of air film...

Homework Statement A converging lens and a diverging lens, separated by a distance of 30 cm, are used in combination. The converging lens has a focal length of 15 cm. The diverging lens is of unknown focal length. An object is placed 19 cm in front of the converging lens; the final image is...

A coin is located 20.0 cm to the left of a converging lens (f=16.0 cm). A second identical lens is placed to the right of the first lens, such that the image formed by the combination has the same size and orientation as the original coin. Find the separation between the lenses. So, f=...

I do not know where to ask this question: For a lens (converging or Diverging), How do i know if magnification is positive or negative?

Will the image of an object inside a gravitational lens, though on the side of the lens that is facing us, be enlarged/reduced in apparent angular width? If so, how is this quantified, and dimensionless GR values may it be related to (e.g. gravitational length contraction factor, etc.)? Will...

Hi, I have been working on this for a little while and think I am approaching it incorrectly. If someone can help, I'd really appreciate it. This is for a basic introductory calculus based Physics class that I am in. 1. Mathematically demonstrate the following equation with no numerical...

Homework Statement I posted this question in Introductory physics section but no one is able to clear my doubt. That is why I have posted it here.Please guide me. # I have some doubts regarding achromatism of lenses: 1)If we want to form an achromatic combination of lenses in which both...

I got new lenses today for my glasses. It says: Sphere: OD -3.75 OS -3.75 I was walking around the mall for an hour while they made my lenses blind as a bat. :bugeye:

I am trying past paper exam questions for my wave optics paper and have got stuck on this question. Two identical biconvex lenses of refractive index 1.5 and with radius of curvature of 20cm on each side are to be used to produce a real erect image of incoming parallel rays. If the image is...

What is axial thickness? Is it the thickness between the two principle planes of a lens or is it just the thickness of the lens? I need the correct defintion to finish a problem.

What are the current technical difficulties that prevent us from focusing x-rays with lenses?

Hello everyone, I'm confused on this issue. How can I tell if the focal length is going to be postive or negative when 2 lens are combined like the ones below: Here is the directions: You grind the lenses shown in Figure 34-49 from flat glass disks (n = 1.5) using a machine that can grind a...

I was wondering if magnification applies to the vertical and horizontal dimensions, or just the vertical. The following information is about the question I am dealing with. It won't answer my concern above, but give a sens of what is going on. The question is dealing with a thin lens...

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?

Is it okay to wear more than one in each/either eye?

Are considered two identical diverging lenses, each one of focal distance -10cm and separated 25cm. which it is the position of the image of an object located in the infinite? The answer is: Virtual image and to 7,7 cm of the second lens. I need to know how to solve the problem, step by step.

Could somebody please help me on the following questions: 1. A camera with a 50mm focal length lens focuses on a man 1.8m tall standing 40m from the camera. (a) What angle does the man subtend at the camera lens? [I do not know what subtend means] (b) What is the size of the image...

Okay, so I have to do a Lab Report, easy enough, I've done them before, but it isn't so clear, and when I tried doing it, I wasn't sure if I was even doing it right. (Personal Note: DO NOT TAKE PHYSICS CORRESPONDANCE! ><) Anyway, here's what I have to do. The Lab Report is on the...

What are gravitational lenses?

Can someone tell me what sort of equation I would use for this question, I can't use the magnification as I have two unknowns. At least I don't know how to apply the magnification equation to this question. A microscope is made in a tube 25.0cm long. It magnifies 5.00 x 10 to the 2 times...

Hello, here is the problem i am having trouble with. The sun falls on a concave mirror and forms an image 3 cm from the mirror. If an object 24mm high is placed 12 cm from the mirror, where will its image be formed? So far, i have decided that since 1/f = 1/do + 1/di... 1/f = 1/do + 1/3 =...

the image's height? If so, how? I have the formulas, but see no way of making a substitution. If you wanted to know the problem, it states: The focal length of a camera is 35 mm and the radius of the moon is 1.74 x 106 m. Calculate the diameter of the moon's image that appears on the...

Glass lenses behave in the way it is expected to behave when the medium they are in is a vacuum or air. But if the medium is also glass it obviously doesn’t work as a lens. If the density of the medium is higher than that of glass the lens works in the opposite way. The power of a lens...

This is probably a stupidly easy question, but I'm confused so I need to ask about it. :smile: I have this experiment I was doing where I have a light source at one end (which is enclosed in a casing and only let's light get out in the shape of an arrow because of an arrow shaped hole) and...

hey- I've been working on this one for quite some time now and just can't seem to get it: Two converging lenses with focal lengths 10 cm and 20 cm are placed 30 cm apart. Rays from a very distant object are impinged on the lens system parallel to the principal axis. What is the refractive...

Hi i have a question about a lens,im not sure if this is the right place to ask but il ask anyways...please help I am really stuck! Question: An object is placed 24cm infront of a concave mirror of focal length 18cm. Where is the image formed and what is its magnification?Include an...

ok have a look at the pdiagram i drew the thing in the middle is a convex thin lens and to the right is a concave mirror. The arrow on the left stands for the object, the object is placed at 2F1. The convex lens to cancave mirro length is 2(f1 + f2) Find the location of the nature and...

i just bought a telescope and i am in Canada it iz really cold outside and i want to take it outside to look at the stars but someone told me that moisture would get stuck in the lens and it would be ruined can somebody tell me if this is true personally i don't think it would but i don't want...

I just have 2 questions. If you use a mirror under water would the focal length change? And same question, but if you use a lens under water would the focal length change? I was thinking, light rays travel slower in water, so then it difracts away from the normal more than if it was in...

In my area, humidity is where it's at. One of the problems I noticed when grabing my mirror (first time using it) to pack up was the fact that it soaked up enough water that I can't even see myself in it. This explains why it didn't work. I DID NOT WIPE THE LENSES. I just put the...

Okay for the most part I understand the concepts involved but I'm having some trouble with this question. The distance between an object and its upright image is 20.0 cm. If the magnification is 0.500, what is the focal length of the lens that is being used to form the image? Now...

An object pin is placed 20cm in front of a convex lens which is 10 cm away from a plane mirror . An inverted image is found at the same position of the object(above the object). What is the focal length? thanks

Stumped...lol.. A concave mirror has a focal length of 62.4 cm. Determine the object position for which the resulting image is upright and four times the size of the object. What formula do I use for this question? :confused:

is it possible to read infared ink with human eyes. I have seen lenses for cameras but can't find anything for eyes. If so, where is informaiton on this thakns

It's a known fact that when you partially cover a lens (with fabric or something), the image on the other side would look less illuminated, since less light rays go through the lens. However, what happens when you partially cover a concave/convex mirror? Our teacher thinks the same thing...

Hi, I know that when entering a convex lens, light rays bend towards the center due to refraction. But why do they keep bending towards the center once they exit the lens? Should'nt they now bend away from the lens because they are going from a denser to a rarer medium? Thanks SK