# What is Michelson: Definition and 123 Discussions

Albert Abraham Michelson FFRS HFRSE (December 19, 1852 – May 9, 1931) was an American physicist known for his work on measuring the speed of light and especially for the Michelson–Morley experiment. In 1907 he received the Nobel Prize in Physics, becoming the first American to win the Nobel Prize in a science. He was the founder and the first head of the physics department of the University of Chicago.

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1. ### I Why do we always see interference pattern in Michelson interferometer?

In a Michelson interferometer with a monochromatic laser, why do we always see an interference pattern even if we move one of the mirrors? Shouldn't it be a certain distance for which the movable mirror reflects the wave to be in opposite phase with the other wave so that they interfere...
2. ### I Michelson & Morley in Space-Time Diagram: Can't Make it Work

I have tried to draw a simplified diagram depicting the original Michelson experiment. I am only looking at the paths from the beam splitter to the mirrors at the end of the arms and back, Below, you can see the following: A space-time diagram with two space axes (x andy) and one time axis...
3. ### Michelson Interferometer with a lens

Hello everyone, i have a homework but I'm so confused how to solved it , can someone make a solution manual for this homework?, Thankyou.
4. ### B Questions on the Michelson Morley Experiment

I've heard claims the Michelson Morley experiment proves light moves at the same speed in all reference frames. However, after looking through the experimental setup, I do not see how they can make this claim. The entire experiment, from my view, was conducted in Earth's reference frame. His...
5. ### Michelson interferometer -- Plotting experimental data to determine t

See attached images.
6. ### I Understanding Michelson Morley Experiment

Hi all, I’m having a little trouble understanding the Michelson Morley experiment. Questions below. I understand that the light beams in the interferometer were expected to somehow pick up differences in the speed of light when one beam traveled parallel to the direction of motion and the...
7. ### B Beamsplitter in a Michelson interferometer

For a science fair experiment at high school I built a Michelson interferometer that could achieve a single interference state. Now there are two beams exit from such an interferometer, if a dielectric beamsplitter/combiner is used, one beam exits in a constructive state, and the other in a...
8. ### I Michelson interferometer dimensions

hi i want to design michelson interferometer device for measuring small distance movement i am using laser diode with a wavelength 635 nm and power 3 mw can anyone tell me how can i decide the dimensions (from source to beam splitter , for beam splitter to fixed mirror , from beam splitter to...
9. ### I have problem with a mirror on Michelson interferometer

My students and I tried to create a Michelson inerferometer like yours (08557.00). The problem is with a mirror that moves. How did you solve this precise translatory movement? Professor of Physics Nikola Gledić - Technical school Šabac, Serbia Thanks in advantage!
10. ### I Michelson Morley experiment

In Michelson Morley experiment we use a moving mirror to reflect light and then we find out that light moves with c regardless of the speed of the mirror. My question is why do we need a theory to replace the galilian composition of velocities?i mean this can be explained by saying that...
11. ### I Learn Michelson Morley Exp: Best Books Explaining Light's C Speed

I want a book that explains everything about Michelson Morley experiment. The one that says light moves with c regardless of the speed of the source and also the one that says light appeared to move with C for all observers.
12. ### I Amplitudes in a Michelson interferometer

Hello, I am having a hard time understanding a result relating to a michelson interferometer. I always assumed that when the beam hits the wave splitter both resulting waves will have half the amplitude of the original wave. However using this assumption does not give the correct irradiance for...
13. ### Fringe Visibility of Sodium Doublet in Michelson interferometer

Homework Statement The sodium D-lines are a pair of narrow, closely spaced, approximately equal intensity spectral lines with a mean wavelength of approximately 589 nm. A Michelson interferometer is set up to study the D-lines from a sodium lamp. High contrast fringes are seen for zero...
14. ### Fringe-Shift in Michelson Interferometer with a Moving Source

Homework Statement The Michelson interferometer in the figure below can be used to study properties of light emitted by distant sources A source ##S_1##, when at rest, is known to emit light at wavelength ##632.8~ \rm nm##. In this case, if the movable mirror is translated through a...
15. T

### Transmission and reflectivity in a Michelson interferometer.

Homework Statement Sketch and explain the operation of the Michelson interferometer. How is the transmission of the interferometer modified if the amplitude transmission t and reflectivity r of the partially-reflecting beamsplitter are not equal? What happens to the fraction of light that is...
16. ### I Michelson Morley experiment: relativistic explanation

I don't uderstand how, using special relativity theory (time dilatation and length contraction), one can explain why in the Michelson interferometer there is no delay between the two rays in the reference frame where the interferometer is moving. Consider the picture ##2.## Setting...
17. ### Using multiple mirrors in Michelson Interferometer

The number of mirrors typically used in Michelson Interferometer is 2. I am looking up the respective Wikipedia article and MIT's youtube video. I am wondering, for the sake of one of my experiment, whether more than 2 mirrors can be used in the interferometer? I require the traversing mirror...
18. ### I Michelson Morley experiment

Relativity, Resnick Here, for calculating t2 , w.r.t. ether frame, light is moving along the triangular path as shown in Fig. 1.7 with speed c. w.r.t. interferometer frame, light is moving along the straight path with speed c##\hat y## - v ##\hat x## while going up and with speed -c##\hat y##...
19. ### Special Relativity: Rotated Michelson Interferometer

Homework Statement The aether-wind theory of the Michelson-Morley experiment was discussed in class for the special case where the arms of the interferometer (each of equal length L) are parallel and perpendicular to the wind. In this problem we consider the general case for an angular setting...
20. ### B Evolution of Principles: Michelson-Morley, Lorentz & Einstein

Hi forum, I followed through Feynamn's derivation to show the different times taken for light by the parallel and perpendicular paths of the Michelson Morley apparatus. He showed that it took longer for light to go to the far mirror and back if it were parallel to the direction the whole...
21. ### Insights Fabry-Perot and Michelson Interferometry: A Fundamental Approach - Comments

Charles Link submitted a new PF Insights post Fabry-Perot and Michelson Interferometry: A Fundamental Approach Continue reading the Original PF Insights Post.
22. ### Michelson interferometer moves and bright fringes disappear

Homework Statement In a Michelson interferometer, as one of the mirrors is moved, 250 bright fringes disappear into the centre. If the light wavelength was 800nm, how far was the mirror moved? Homework EquationsThe Attempt at a Solution My logic is: If we were to count how many passing bright...
23. ### I Michelson Morley Experiment Light Source

My question is that in Michelson Morley experiment, how they produced the light? what was the light source and has anyone used sunlight as a source yet to re-confirm that experiment? I am interested in sunlight as a source of light due to certain reason... Please if you know kindly mention the...
24. ### I Michelson Morley experiment

By measuring the speed of the light beams through the inferometer michelson morley tried to explain the existence of ether. This was done by measuring light beams's speed. The beams were in different direction. Did they want to say that the beam in the direction of the movement of the Earth...
25. ### B Question about Michelson-Morley experiment

Hi, I think I have a good grasp of the principles underlying the Michelson-Morley experiment, but I am not sure about a detail. In basic textbooks a simplified situation is presented whereby the ether wind is along one of the two arms of the interferometer. Simple classical physics calculations...
26. ### Michelson Interferometer IR Lab Question

I've been reading up on Fourier Transform Infrared Spectroscopy and the Michelson Interferometer. My main sources are "Principles of Instrumental Analysis" by Skoog etc and Fourier - Transform Infrared Spectrometry by Griffiths and Haseth. I believe I understand the theoretical principles...
27. ### I Why is the medium in the Michelson Morley experiment ignored

Normally in explaining the aether model of light it is said that all waves need a medium, so just like sound uses air, light uses the aether. To my understanding sound can travel through gas, liquid and solids just fine without air being partially entrained in the materials. Sound does not use...
28. ### Michelson interferometer

I'm reading about an experiment done with a Michelson interferometer. The aim is to measure the thickness of a piece of plastic. They use white light, so the central fringe in the interference pattern, corresponding to equal path lengths in the two beams can be used as a reference. Why does that...
29. ### Optics: Center of Fizeau Fringe? Michelson Interferometer

Hello everyone, i am simulating a Michelson interferometer, where one mirror is slightly tilted, see picture.. This results in circular arcs / hyperbolic cross-section fringes. The center of these fringes depends on the focal length i am using, see picture. Is there an analytical expression for...
30. ### Michelson Interferometer ring contraction

I have been trying for hours to understand what is physically causing the interferometric rings to contract when the separation of the mirrors is reduced. From the equation: m\lambda = 2Lcos\theta, where m is the number of fringes, if we consider just one fringe at a fixed wavelength...
31. ### Energy conservation and michelson interferometers

What happens to the energy of a laser beam when it completely deconstructively interferes with itself in a michelson interferometer?
32. ### Puzzle of negative result of Michelson Morley experiment

HI all How can Michelson itself predicted contraction of length and Einstein about constancy of light from negative result of MM experiment. forget about existence of ether, light speed always same in moving frame of reference and importantly in any direction so how can one except shift in...
33. ### Michelson Interferometer (Zero Path Difference)

Homework Statement A Michelson interferometer is illuminated with a laser with a wavelength of 514.5nm. A Haidinger fringe pattern is photographed with a lens of focal length 55mm. The diameter of the two adjacent circular fringes in the image are 1.53mm and 2.62mm. How far would the mirror...
34. ### Michelson Interferometer

Homework Statement My personal question: What does a Michelson interferometer tell us? The actual problem: A Michelson interferometer is used to precisely measure distances of the order of 1 mm using a laser of wavelength 632.8 nm. a) If the motion of one mirror is 1 mm, what is the...
35. ### Michelson Morley experiment

I'm a little confused about this. I know how to derive the expression t≈lv2/c3 for the time difference between the arrival of the two beams due to the presence of an ether, with the Earth moving at speed v through the ether, and l the distance between the beam splitter and each mirror. This can...
36. ### Michelson Interferometer - calculating errors

Homework Statement Part (a): Find an expression for intensity, interference phase and total change of interference phase. Part (b): Find an expression for <L1>/L0 and its error. Part (c): Find an expression for Δø1 and proportionality constant. Part (d): Find an expression for n(0) and α...
37. ### Michelson interferometer fringes

Since 2 splitted beams meet at ONE spot later on, we have just one beam which flows to the detector, therefore I expect to see just one light spot, where the BRIGHTNESS is changing depending on at which phase 2 beams meet. Pattern with fringes happens when we have multiple sources, like Young's...
38. ### Michelson Interferometer: Optics

Homework Statement A Michelson Interferometer has incident light in range 780-920 nm from a source. Intensity as a function of x (distance from central maxima) is given by: I_{(x)} = 3I_0 + 3I_0 cos(K_1x) cos (K_2x) - I_0 sin (K_1x) sin (K_2x) where ##K_1 = 1.3 x 10^7 m^{-1}## and ##K_2 =...
39. ### Unraveling the Michelson-Moorley Experiment

The Michelson Moorley experiment to detect the presence of aether is the main experiment that gave rise to the theory of relativity. I've been trying to understand this experiment. The idea of the experiment was to split a beam of light and then align one the split beams with the aether and...
40. ### Doubt in Michelson Morley experiment

Hi All, I studied about Michelson Morley experiment in my graduation in the compulsory Physics paper. I had Computer Science major(not a Physics guy:frown:), anyways this question came in my mind during my graduation time and may be because of my misinterpretation however couple of days ago...
41. ### Need some help trying to understand the Michelson interferometer

Refer to the second diagram on this website http://electron6.phys.utk.edu/optics421/modules/m5/Interferometers.htm Using monochromatic light at first, you produce an interference pattern using the Michelson interferometer. If you set the relative tilt of the mirrors so that they are...
42. ### Michelson interferometer average power derivation

Homework Statement Using the trig product identity, cosαcosβ=\frac{1}{2}[cos(α+β)+cos(α-β)], show that the time-average power at the detector can be written as Pavg = 1+cos(δ) That = is supposed to be a proportional symbol. Homework Equations Other than the ones given in the problem...
43. ### Question about Michelson Morley experiment

Hi everyone. I'd like you to help me make sense of a question I found about the Michelson Morley experiment. This is it: "Explain how and why the uncollimated light rays form interference fringes? Can you say what would happen if the rays were collimated?" Does this question even make...
44. ### Why can't I see fringes with eyepiece in my Michelson Interferometer?

Hello Forum I have constructing a Michelson Interferometer using sodium light. For viewing the fringes, I have used spectrometer telescope with objective lens of 178mm focal length, 35mm dia and eyepiece 15X. I can see the localized fringes when I view through the objective glass but without...
45. ### Michelson Interferometer

Homework Statement The distance between the movable mirror and the beam splitter in a Michelson interferometer is increased a small amount. When this happens, you see 200 dark fringes move across the field of view. If the incident light was 600nm, by how much was the mirror moved (in...
46. ### Why is the equation for delta t in a Michelson interferometer 2(L/v - L/c)?

Homework Statement In one arm of a Michelson interferometer the light passes through a glass tube of length L which contains air. The air is pumped slowly out of the tube and during this process it is found that the intensity of light reaching the eye has increased and decreased n times...
47. ### Why do Michelson interferometer usually needs 2 mirrors?

I've been wondering this for quite some time. Why do a typical set-up of Michelson interferometer usually requires 2 mirrors? Why not one for adjustment? Why not just shine the laser through the beam splitter? Thanks.
48. ### Michelson morley experiment.

I am having difficulty understanding why when the apparatus in the figure on page 448 (http://web.physics.ucsb.edu/~phys22/K%20and%20K%20Sections/KK_Chapter11.pdf [Broken]) is rotated 90 degrees the time delay is twice what it was before. When I think about I immediately think it would be the...
49. ### Michelson morley experiment.

Homework Statement It isn't really a homework problem rather http://spiff.rit.edu/classes/phys200/lectures/mm_results/mm_results.html If you search " After they rotated the device by 90 degrees, the arm which was sideways to the ether would now be going with-and-against the wind...
50. ### Why unequal fringe width in Michelson interference pattern?

why unequal fringe width in Michelson interference pattern?