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1answer
17 views

Calculated focus of an asymmetric bi-convex lens

So I've been working on modeling an optical system using ray tracing. I've finally gotten to the point where I am testing things however I've come across something I'm not entirely sure of. I'm ...
0
votes
0answers
23 views

Question about transmission of paraboloidal light waves in bi-convex lens

The question is as follows: Show that a paraboloidal wave centered at $z_1$ is converted by a lens of focal length $f$ into a paraboloidal wave centered about $z_2$, where $\frac1{z1} + \frac1{z2} ...
1
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0answers
17 views

Polishing Spherical Refracting surface vs Lens

My text book states that When we polish a spherical refracting surface (sphere) it doesn't behave as spherical surface and mirror .It still behaves as spherical surface. The polished side is just ...
-2
votes
1answer
82 views

(7) Will a nearsighted person who wears corrective lenses in her glasses be able to see clearly underwater when wearing those glasses? [closed]

Will a nearsighted person who wears corrective lenses in her glasses be able to see clearly underwater when wearing those glasses?
0
votes
0answers
38 views

Raytracing on convex spherical surface, where n1>n2

I'm reading my textbook and I'm trying to figure the ray tracing of a single point of this one case that the book doesn't cover. My question is, what does the ray tracing look like when we have a ...
1
vote
2answers
72 views

Does phase change occurs on refraction at a lens?

There is no phase change between refracted (transmitted) rays and incident rays, according to boundary conditions of electric field and magnetic field, in accordance with the Maxwell's equations and ...
0
votes
0answers
29 views

The ideal shape of a plano-convex lens

What's the type of the ideal shape of a surface of a plano-convex lens to focus a parallel beam at the point? Considering the lens turned its flat side to a beam. Surely it must be aspheric: ...
3
votes
1answer
115 views

Which of these 2 methods for calculating the focal length of a concave mirror is more accurate?

I have done an experiment to measure $f$ the focal length of a concave mirror. I have a list of 8 values for $u$ the object distance and 8 values for $v$ the corresponding image distance. I ...
1
vote
1answer
152 views

How is the image distance negative?

Following is a problem from book: "The near point of a person's eye is 53.0 cm. To see objects clearly at a distance of 24.0 cm, what should be the focal length of the appropriate corrective lens?" ...
0
votes
3answers
91 views

Why do lens (convex) not introduce any path difference to light incident on it?

My understanding is that the top rays spend less time inside the lens where the speed of light is slow and the middle rays spend more time inside the lens so the time is kind of compensated . But I'm ...
2
votes
2answers
44 views

Light hitting a GRIN (Gradient-index) lens at the optical angle

In the image below, rays of light are hitting the GRIN (Gradient-index) lens at the optical angle and then converge towards the optical axis. Why do they do this? The refractive index is only a ...
1
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0answers
39 views

working to understand virtual images

I'm starting to understand how to use lenses a bit more, but I'm still pretty lost. I'm building a project that's extremely similar to this one with the implementation. I think my biggest challenge ...
2
votes
2answers
81 views

image formation by lenses

Why is the image formed by an object as described in the picture can be derived only from these three ray of lights?Every point on the object has multiple ray of lights going in every direction, how ...
0
votes
1answer
247 views

What will happen if the refractive index of lens is less than unity? [duplicate]

Generally the refractive index of any lens is greater than air. My question is what will happen if the refractive index of lens is less than unity?
1
vote
2answers
839 views

Focal length of magnifying glass

Why a magnifying glass has a short focal length? According to its work the object must be between the focus and the optical centre, a large focal length will favour it, then why is it so?
0
votes
1answer
32 views

Raise index of refraction of spherical lens

What happens to focal length and aperture of a spherical lens if you raise the index of refraction of the glass?
2
votes
1answer
57 views

Refractive screen for myopia [closed]

Is it possible to create a screen for a computer monitor to allow a Myopic person to see the screen without glasses?
0
votes
1answer
165 views

Looking through a glass hemisphere [closed]

I've found the following question on IsaacPhysics.org . I've been working on it for a couple of hours but I cannot figure it out. A looking glass is used to read an ancient scroll. This lens has a ...
2
votes
1answer
101 views

What refractive index should be used while calculating the focal length of lens using lensmaker's formula?

Suppose a lens is half dipped in liquid. Then should the refractive index of liquid with respect to air should be taken. Or should refractive index of glass wih respect to liquid be taken. Or perhaps ...
2
votes
0answers
34 views

Geometric optics limit in lens design [closed]

What is the rule-of-a-thumb ratio of lens' thickness to wavelength at which they can be designed using ray optics approximation? (The thickness is more relevant to gradient index lens, homogeneous ...
1
vote
0answers
64 views

Biconvex lenses in 2 media

The question is what is the formula of the focal length of a biconvex thin lens if object medium is water and the image medium is air. I know that we have: 1/f = (n-1)*(1/R1 - 1/R2) , if the medium ...
1
vote
1answer
70 views

Can we see through the central obstruction of a lens?

I have a very basic question in optics inspired by this article from the University of Stanford which clearly states that one should see a light source through a mask in the middle of a lens if the ...
0
votes
2answers
188 views

Confused with image and object distance in lens

I am not sure why S is negative in this image. How do we determine whether it's negative or positive?
0
votes
1answer
24 views

Making a lense using an array?

Would it be possible to build a lense out of array elements with a higher refractive index inter spaced with void elements eg a matrix of glass with air. I imagine that the spacing would have to be ...
2
votes
2answers
2k views

How to measure the refractive index of a lens?

how to measure the refractive index of a lens? (a simple method) I want to find a simple method to measure the refractive index of a lens.
2
votes
1answer
103 views

What would happen if the aqueous and vitreous humour of a human's eye are replaced by some harmless transparent liquid of different refractive index?

The title says it all. What would the person be able to see? Note By harmless, I mean that it is non-corrosive, non-toxic, etc. The liquid doesn't cause any biological damage to the eye or any other ...
1
vote
1answer
2k views

Refractive index and focal length

When the refractive index of medium is greater than the lens then what will happen to the focal length of the lens?
1
vote
1answer
1k views

Lensmaker's equation for thick lens in two different media

I've been looking around and I've found the lensmaker's equation for thick lens to be $$\frac{1}{f} = \frac{n_{lens} - n_{m}}{n_m} \big( \frac{1}{R_1} - \frac{1}{R_2} + \frac{n_{lens} - n_m}{n_m} \...
-1
votes
1answer
71 views

Refraction by a thin lens

What happens if the radii of curvature of the two spherical surfaces of a thin lens are equal? According to the formula, $$1/f = (n - 1)(1/R1 - 1/R2) $$ (Where $n$ is the refractive index of the ...
1
vote
0answers
188 views

Finding a Lens System Matrix for a Planar Concave Thick Lens

How can I go about determining the lens system matrix for a planar concave thick lens? I analyzed that a light ray first enters the lens and refracts, then it goes through the lens, and then it ...
0
votes
1answer
76 views

Combination of lens

In the above diagram, let the refractive index of concave lens be $n_1$ and of convex be $n_2$.So in order to apply lens maker formulae for it, will I have to assume air separation between the lens? ...
1
vote
2answers
790 views

Does the position of the final image in a multiple lens system found by the thin lens formula always agree with the ray diagrams?

For example, in the figure given below let the object be at O, the eye of the observer at E and the pole of the convex and concave lenses be P and P' respectively. Assume the object is placed such ...
2
votes
2answers
235 views

Why does refraction make something look closer with an incident angle of zero? [closed]

The gaussian formula for a single spherical surface is defined as $$ \frac{n}{s} + \frac{n'}{s'} = \frac{n'-n}{R}$$ When the radius of curvature, $R$, is ...
1
vote
0answers
249 views

Determine the focal length of a biconvex lens [closed]

I'm struggling to find any information on this topic online. I've been asked to find the focal length of a biconvex lens with these specifications: Refractive index: 1.5 Total Height: 7.5cm Radius of ...
3
votes
1answer
519 views

“fish appear to be 30% smaller because of the curvature of the tunnel”

I recently visited an aquarium in Malaysia and there was a sign saying that the exhibits in their main tank appear to be smaller by 30% especially when viewed through their tunnel (https://www.youtube....
11
votes
2answers
2k views

Why do convex lenses not disperse light like prisms, given that entry and exit points aren't parallel?

I understand that light entering a parallel block of glass at a non-90 degree angle will cause dispersion of colours within the block but that these will be refracted by the same degree upon exit so ...
2
votes
1answer
72 views

Why can't rainbows form at the start of a storm?

I was recently at a park looking at the gorgeous scenery. I looked above and saw thick grey clouds covering up 3/4 of the sky. The sun's light is still visible for 1/4 of the sky, and it looks low ...
0
votes
3answers
282 views

Why bi-convex lens give ignition?

Bi-convex is mostly used type of lenses.It can burn paper with help of sunlight.But why? Why bi-convex lens can give ignition when other lenses can't?
1
vote
1answer
69 views

Is it possible to construct a lens which focuses all the light rays from an extended object in one point?

A perfect lens focuses the light rays from an extended object (in a plane at a constant distance from the lens), in the focal plane corresponding to the distance of the object. Now there is an ...
0
votes
1answer
201 views

Geometric optics multiple lenses

I am confused on how light rays behaved in this figure, specifically when it passed through the diverging lens. Why would the light rays converge when it passed through the diverging lens, when it ...
-1
votes
2answers
60 views

Geometric optics- lenses

I was wondering why would light rays converge at a biconvex lens and diverge at a biconcave lens? Is it concerning on how light rays behave in a convex or a concave mirror? Also, is it possible to ...
0
votes
1answer
753 views

Refraction of light In convex lenses [duplicate]

I came across this image when researching refraction in lenses. I can't understand why the light does not refract at the points which I have marked with burgundy arrows even though it is crossing a ...
3
votes
0answers
3k views

What is Curvature of eye lens?

I wanted to know what do we mean by "curvature of eye lens", is it the reciprocal of $r$ i.e $c=1/r$ or is it synonymous to radius of curvature of the eye lens. Moreover how does aperture relate to ...
0
votes
1answer
10k views

Why can't concave lenses be used as magnifying glasses?

I see why convex lenses work, but why can't concave lenses work? The light from an object diverges, making it wider, so technically that should make the object bigger, shouldn't it? Why isn't this the ...
0
votes
3answers
3k views

Can focal length of convex lens be negative?

Is focal length of convex lens negative when it is surrounded by a medium with greater refractive index than that of lens?
3
votes
4answers
5k views

A lens inside a liquid is not visible. Why? [closed]

Are lenses inside liquid water invisible?
3
votes
2answers
3k views

Light refraction in a glass sphere: Is there a focus or not?

Recently, someone told me to pay attention when hanging a wind chime containing a glass sphere in front of the window, because a focus point might be formed on the curtains which might on a sunny day ...
0
votes
2answers
217 views

Image formed when two imaginary rays are extended to meet at a point

An object is placed at a finite distance from a concave lens. Given are the two ray diagrams. Is the second ray diagram possible? If yes, that must be an enlarged, virtual and inverted image; if no, ...
0
votes
1answer
51 views

Refraction of light by lens

Im thinking if I can obtain parallel rays after the light rays pass through the convex lens by moving the lens closer to the light bulb or by having a lens with a larger focal length. Which method is ...
3
votes
2answers
1k views

Are xkcd's and/or Pink Floyd's prism optics correct?

In xkcd # 964 "Dorm Poster", the cover art from dark side of the moon is "completed" with another poster that performs the inverse action: A lens is used to turn the diverging color rays from the ...