The subfield of optics in which light propagation is approximated in terms of rays. It mainly includes reflection and refraction on surfaces.

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Concave lens path of ray

What will be the path of ray passing through the first focal length of a biconcave thin lens kept in air? I know that a ray passing through focus or appearing to pass through focus of a thin lens ...
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2answers
55 views

The image of a wall clock is to be obtained on the opposite wall 2m away by the means of a convex lens. What is the minimum focal length required? [closed]

I'm in 10th grade and this question came in my physics test. Nobody was able to answer this question correctly except my physics teacher who says that the answer is 2m. My answer is that there should ...
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2answers
52 views

Reflection law (from Fermat's principle) for arbitrary surface

Normally reflection law is deduced from Fermat's principle (e.g. here) for a planar mirror. Also some other mirror surfaces can be studied (e.g. here they treat a spherical mirror). Is there some ...
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48 views

How to solve this problem : A glass sphere of radius 1 m and refractive index 1.5 is silvered…? [closed]

Problem: A glass sphere of radius 1 m and refractive index 1.5 is silvered at its back. A point object is kept at a distance of 1 m from the front face, as shown in the figure. Find the position of ...
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3answers
91 views

Application of Snells law

What i know about snell's law: It is applied when a ray of light meets the interface of some other medium and we can find the fourth quantity if we know any of the three quantities in the following ...
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1answer
24 views

Signal loss in non-reflected light through a tube proportional to square of the length?

Reading a patent I came across the claim: "...a portion of light intersecting the inner metal surface is not reflected, resulting in a loss in signal intensity... the signal loss is proportional to ...
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2answers
107 views

Why do you need at least two rays to form an image?

Why isn't enough one light beam to form an image in your retina for example?
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3answers
62 views

Bending of light [closed]

Why does bending of light(diffraction) occur?
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26 views

Using thin needle for object and thick needle for image

I have performed an experiment to determine the focal length of a concave mirror in my school lab. It consists of an optical bench with two needles, one as object and one image. We basically try to ...
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1answer
34 views

How do we call in English scientific terms the Fermat's principle about back and forth light traversal?

We know that the path followed by the light from point A to point B is independent of the direction of propagation of light. This is what is called in French "le principe de retour inverse de la ...
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1answer
156 views

Total number of primary maxima in diffraction grating

I am trying to determine the total number of primary maxima that can be observed when light of wavelength 500 nm is incident normally on a diffraction grating, with the third-order maximum of the ...
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1answer
52 views

Calculating angle of refraction of water in this lab setup? [closed]

The setup of the experiment is as drawn in the picture (where the red circle is a rotating disk, the box is a laser and the straight line the laser beam and the semi circle in the middle of the ...
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2answers
120 views

Can focused light be treated as a point source?

Imagine there is a uniform, collimated beam coming from a distant light source. This beam passes through a lens and is focused to a point at the focal length. Can this "point" be treated as a point ...
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0answers
75 views

Derivation of the formula related to number of images?

I have read in my book that if two mirrors are inclined at an angle $\theta$, if 360/$\theta$ is even , the number of images is given by (360/$\theta$) -1 What is the derivation of this formula? I ...
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1answer
25 views

Light and Visibility [duplicate]

It is difficult to see through a closed glass window from the inside of a well lighted room, when it is dark outside. However it becomes relatively easy to see outside, when the light in the room are ...
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0answers
71 views

Which Method for finding velocity of an object in the mirror is correct? [closed]

My Professor asked a question, "A person is seen jogging in a rear view mirror of focal length $1$m. He is at a distance $39$m from the mirror. His jogging speed is given to be $5 \frac{m}{s}$. ...
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1answer
98 views

How to determine the radius of curvature of a convex lens?

Suppose there is an equi-convex lens made of glass which has a focal length ($f$) of 30cm. Then, can we not say that the radius of curvature, $R$ of the lens is twice the focal length, i.e. $R = 60cm$?...
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4answers
39 views

What is the distinction between a “ray” and a “wave” in optics?

What is the distinction between a ray and a wave in optics? From what I can gather, the only discernible difference is in nomenclature, where a ray simply refers to an EM wave with short wavelengths. ...
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16 views

The image of an object through a curved surface

We have a curved surface, separating two different medium, with refractive index n1 and n2. We know the radius R of the curve,then how can we find the position v of the image? I read that the ...
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6answers
6k views

Do people wearing glasses have different field of view than those who don't?

There is one thing I sometimes wonder about ever since I was a child. Do people who wear eye glasses see objects in different size than those who don't?(Technically different size means different ...
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0answers
45 views

Rings of light around a jet [duplicate]

When an obstacle is put in the path of a liquid jet, some standing waves are created upstream of the obstacle (see the pic) or we can say a similar form like this for them ( the wavelength of ...
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0answers
46 views

Prismatic shaped rear view mirrors

To reduce the intensity of the incident light, prismatically shaped rear view mirrors are used in cars with a day-night switch which changes the angle such that instead of the polished surface ...
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0answers
71 views

Lens formula and Lens maker's formula

When we derive the formula for lens and lens maker's formula using the formula for refraction at spherical interface $$\mu_2/v - \mu_1/u = (\mu_2-\mu_1)/R$$ we put $u$ to be $-u$ as it is on the left ...
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3answers
605 views

What determines the sharpness of a shadow?

What are the factors that affect the sharpness of a shadow? I would think that the distance between the light source and the object, the distance between the object and the shadow, and the size of ...
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2answers
151 views

Why doesn't a Gaussian beam converge to a point?

No matter what lens is put in the beam path of a Gaussian beam, it will always go through a waist of non-zero width. Why not just a point? I know the maths, I'm wondering whether there is any ...
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0answers
39 views

Refracting telescope image formation

I'm having some trouble understanding how a refracting telescope forms a magnified image for an object that is not assumed to be infinitely far away. I drew this ray diagram: And as you can see, a ...
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160 views

Image formed by a Prism

A series of questions that came in my mind after I saw a question So here it goes first the questions that have made me confused : 1) How image is formed by the prism? 2) When we take different ...
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2answers
69 views

Are these reflected rays really parallel?

I have read that if an object is placed on the focus of a concave mirror (assume that the object is a vertical line placed on the focus), then the image will be formed at infinity. Here’s a diagram. ...
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1answer
45 views

pinhole in projector screen

Consider a conventional slide projector projecting a properly focussed static image from a photographic slide onto a conventional screen, with a second screen placed a short distance behind that one. ...
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1answer
30 views

Do all thermal radiators have the same surface brightness?

Imagine I heat a piece of metal to 1000K. It will be red hot and will emit black body radiation corresponding to this temperature. But what about the brightness? Assuming the bulk is opaque, does it ...
18
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1answer
545 views

Do light waves precisely follow null geodesic paths in General Relativity?

In special relativity one may show that a plane wave solution of Maxwell's equations (in a vacuum), of the form $A^a=C^a\mathrm{e}^{\mathrm{i}\psi}$ has the following properties: The normal $k:=\...
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1answer
567 views

Rayleigh-Plateau instability and optic [closed]

Let a liquid jet fall onto a surface. If the contact point is illuminated by a lase beam, rings of light around the jet can be observed . (pic.1) and we know it that the reason of this phenomenon is ...
2
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2answers
168 views

Experiment to find the circle of least confusion (optics)

I want to conduct an experiment where the circle of least confusion (wiki ref) occurs for a lens. Suppose that I shine white light onto the lens and I know the lens EFL is lets say 100 mm, in order to ...
3
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1answer
55 views

100x magnifying optics system for short laser pulse

I am now designing an experiment that consists of a 400 nm short pulse (~300 fs). In the experiment, we need to magnify the transverse profile of the pulse by 100x. That's the problem. I was ...
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45 views

Balance lens tilt aberration

Given a doublet (singlet in reference figure), if the rays enter at an angle with respect to the origin axis, we would see a shift of focal length for blue and red. A known optical jitter How could ...
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1answer
151 views

Combination of mirror and lenses [closed]

I am a keen learner of physics, but I am unable to solve problems involving lenses and mirrors together. please can anybody tell me the method to solve these problems? for instance let us take a ...
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2answers
51 views

Let's suppose I am to display the letter R on mirror as well water , will I get the same images?

As far as my practical experience goes both look quiet the same when an image of any object is formed on them, yet I wanted to be ascertained is there any actual visible differences between both the ...
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1answer
34 views

Encoding multiple images in 1 beam

I am doing some research involving geometric optics. I need to reduce an image in size so it fits a rotating mirror we are using. I came up with the idea of projecting the focal plane on the mirror, ...
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0answers
15 views

Why to use the sign convention while solving problems as the mirror-formula itself is derived using the sign convention? [duplicate]

When we derive the mirror equation of concave mirror, i.e.,$\frac{1}{u}+\frac{1}{v}=\frac{1}{f},$ we've already used the sign conventions. Then why to use the sign conventions again while solving a ...
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0answers
140 views

Velocity of image formed by a spherical mirror in Y axis

If an object is moving with velocity $v_0$ along the positive Y axis in front of a convex mirror of focal length $f$ at a horizontal distance $u$ from the mirror's pole, what will be the velocity of ...
3
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1answer
445 views

Why doesn't a backward wave exist? [duplicate]

Huygens principle says every point of wavefront emit wavelet in all directions. Then why does a back ward wave not exist? Can any expert tell real answer? On different sites I get different and ...
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0answers
30 views

Effect of introducing lens on Fringe width

Suppose I have a light source of wavelength 400 nm. The slits are placed at a distance 1 mm apart. The distance between the slit plane and the screen is 50 cm. So that makes the fringe width, $\beta =...
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46 views

How to collimate a wide-field from a classical Cassegrain telescope?

I have a 0.25 degree field-of-view Cassegrain telescope (see below) that I'm trying to collimate, i.e. make the diverging beam afocal, not collimate in the sense of aligning M1-M2. I can do this with ...
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0answers
46 views

Aquarium/refractive indices/detector

Quick question: I'm currently fiddling around with this homework of mine and I seem to be lacking some basic optics knowledge apparently. An aquarium is filled with a fluid as seen in the figure ...
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0answers
202 views

A small object faces the convex spherical glass window of a small water tank, find the final image?

I was hoping you guys could look over my solution to this question. A small object faces the convex spherical glass window of a small water tank. The radius of curvature of the window is 5cm. The ...
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0answers
49 views

Trapping force in optical tweezer

I am reading a paper on theory of optical tweezers in ray optics regime by A. Ashkin. For reference "click here". It is given that Gradient force $F_g$ is directed perpendicular to the light ray and ...
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0answers
25 views

Method of Transformed Impedances

So I am taking an advanced optics class at the moment, using the book Lasers and Electro-Optics by Chris Davis. At one point, while explaining the concept of impedance, he mentions something called ...
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4answers
219 views

Shining a laser onto a mirror

Theoretically, if I shined a laser at a mirror at an angle of 0 degrees so that the light was perfectly reflected back to the light source, then I should not be able to see the light because it is not ...
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1answer
45 views

Ray optics : Circular mirror with reflecting surface on the inside

A light ray enters through an infintely small hole and gets reflected as shown. After how many reflections will it emerge out again? (It can come out in any orientation). Will it emerge out for any ...
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2answers
85 views

What makes a lens a lens?

I am asking about the way that a convex lens works. All the lenses I have ever seen were solid glass or solid plastic. If I have a convex sheet of clear glass or of clear plastic, shaped into a ...