Experiment Definition and 1000 Threads

An experiment is a procedure carried out to support or refute a hypothesis. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs when a particular factor is manipulated. Experiments vary greatly in goal and scale, but always rely on repeatable procedure and logical analysis of the results. There also exists natural experimental studies.
A child may carry out basic experiments to understand how things fall to the ground, while teams of scientists may take years of systematic investigation to advance their understanding of a phenomenon. Experiments and other types of hands-on activities are very important to student learning in the science classroom. Experiments can raise test scores and help a student become more engaged and interested in the material they are learning, especially when used over time. Experiments can vary from personal and informal natural comparisons (e.g. tasting a range of chocolates to find a favorite), to highly controlled (e.g. tests requiring complex apparatus overseen by many scientists that hope to discover information about subatomic particles). Uses of experiments vary considerably between the natural and human sciences.
Experiments typically include controls, which are designed to minimize the effects of variables other than the single independent variable. This increases the reliability of the results, often through a comparison between control measurements and the other measurements. Scientific controls are a part of the scientific method. Ideally, all variables in an experiment are controlled (accounted for by the control measurements) and none are uncontrolled. In such an experiment, if all controls work as expected, it is possible to conclude that the experiment works as intended, and that results are due to the effect of the tested variables.

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  1. Jilang

    Two slit experiment with a wavy screen

    I was wondering if the two slit experiment has been performed with a wavy screen, the screen being modulated in such a way as to compensate for the difference in the phases of the paths from the two slits. If so what was the result in terms of the angular distribution? If not what would it be...
  2. Tom B

    Two Slit Experiment: Detectors

    I understand the two slit experiment and the outcome, but where I am confused is how the detectors work. It seems to me that a very simple explanation of the result differing due to the presence of the detectors is that somehow the detectors interfere with the path of the electrons. By...
  3. A

    Requirements for an observable pattern in young's experiment

    Homework Statement It's not in fact a question of homework but something I have been wondering but cannot get answers about the requirements for an observable pattern in young's experiment: 1. Polarisation: In my study, the book derived the intensity function of light assuming the light beams...
  4. shpotes

    What is the Best Experiment to Illustrify the Law of Universal Gravitation?

    I want to explain the law of universal gravitation but i need an experiment to ilustrate it, any can help me? What do you think are the best gravity experiment?
  5. ToonBlue

    Simulation result vs actual experiment result

    Homework Statement Let said I have found out the ripple output voltage for a given circuit using a simulation software and it gives me 10V + and then when I do the actual experiment , I got about 7.8V for my output ripple voltage. With a difference of more than 20% , does the reading i get...
  6. N

    Double slit experiment exposed?

    http://www.pnas.org/content/109/24/9314.full According to the experimenters they have found out which path the photon took and still observed the interference pattern. So they know that the particle went through the left or right slit but at the same time saw the interference pattern built up...
  7. V

    Observer Effect hype in Double Slit Experiment

    I don't know if you physicist out there knows it, but the statement that observing something changes its state is having a drastic impact on the less informed populace at wide. An example, one of the most popular Quantum Physics video on youtube <Link to video not acceptable under PF rules...
  8. N

    B Weak measurement in double slit experiment gives which path

    In 2012, experimenters showed that when two entangled photons separate and when one goes through the double slit, we can tell which slit it went through and see that they still created an interference pattern because the photon that it was entangled to tells us which slit it went through. What...
  9. N

    Position and momentum of particle in double slit experiment?

    In the double slit experiment, what is the position and momentum of an electron/photon? Is the position of the electron/photon which slit it went through? And is the momentum of the electron/photon the wave like interference pattern detected on the detector screen?
  10. libbytam

    Why Is the Angle 5.6° in Young's Double Slit Experiment?

    Homework Statement In a Young's double slits experiment, a monochromatic light source of wavelength 700nm is used and the separation of the slits is 0.1mm. If 15 bright fringes are observed, what is the angle subtended by those fringes at the centre of the double slit? A. 6.0° B. 5.6° C. 5.2°...
  11. Y

    Need help with physics experiment (Speed of sound)

    < Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > Last week we had to conduct an experiment with the aim of determining the speed of sound. I decided to play with doppler effect. I was more or less sure what I had to do but then the teacher came...
  12. D

    Conclude Collision Experiment: Car Mass & K.E.

    Homework Statement Car 1 (500g) collides with car 2 (500g). The initial velocity of car 2 is 0. The cars stuck together after the collision. I have to come to a conclusion about the results that i got. Homework Equations Kinetic energy before: 0,233 Kinetic energy after: 0,125 Delta...
  13. J

    Random experiment and sample space

    Homework Statement [/B] Consider a random experiment with a sample space S={1,2,3,⋯}. Suppose that we know: P(k) = P({k}) = c/(3^k) , for k=1,2,⋯, where c is a constant number. Find c. Find P({2,4,6}). Find P({3,4,5,⋯}) Homework Equations For any even A, P(A) ≥ 0. Prbability of the...
  14. D

    Collision Experiment: Momentum, Impulse and Conclusions

    Homework Statement [/B] My class had a lab where we had to push a car toy and then let it bounce back. The on the computer we got a diagram on the impulse and then another diagram with position on y axel and time on the y axel. Then we had to make a chart on the impulse and the momentum before...
  15. J

    Does centrifugal force affect weight at different latitudes on Earth?

    As a result of various searches on the Net, I have ended up here on this fantastic site. Specifically, it was an old 2008 thread in which was closed, so in order for me to expand on such discussion I've decided to make my own thread; by which I will go a slightly different direction with...
  16. M

    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...
  17. D

    Bell inequality violated with classical light in experiment

    https://www.osapublishing.org/optica/fulltext.cfm?uri=optica-2-7-611&id=321243 "In our experimental test, we used light whose statistical behavior (field second-order statistics) is indistinguishable from classical, viz., the light from a broadband laser diode operating below threshold. Our...
  18. B

    Experiment of water defection with a charged rod

    Homework Statement A student designs an experiment to measure how electrically charged a plastic rod is. She knows a charged rod will deflect a stream of water from a tap. The student plans to measure the angle of defection of the water stream when she brings the rod towards it. She expects...
  19. En Joy

    Thought double-slit experiment

    In Young’s double slit experiment, if we use a single electron, then the electron-wave would divide itself into two wavelets due to two narrow slits. Similarly would the electron-matter divide itself in that experiment? If it would not, then through one slit, both the electron-wave and...
  20. votingmachine

    Who would be interested in an EPR thought experiment?

    If a thought experiment with hidden variables gave the same results as EPR experiments, would that be a publishable (even if minor) contribution?
  21. N

    Observed interference in afshar's double slit experiment?

    In afshar's experiment, it shows that the single photon goes through only one of the slits and produces an interference pattern. How is this possible? In this experiment, do we really know which slit the photon went through?
  22. O

    Physics Experiment Help (Torque, Angular Momentum, etc)

    < Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > Hey, So I am not sure if this is in the right section but feel free to move it. We are conducting an experiment at school at the moment and are having difficulty understanding all the theory...
  23. D

    Young's double slit experiment: Determine thickness of mica

    Homework Statement A sheet of mica ( approximate 6-7 µm) covers one slit of a double-slit apparatus and has a n= 1.582. There is a central maximum of 539 nm. What is the exact thickness of the sheet of mica? Homework EquationsThe Attempt at a Solution I think you can solve this with the...
  24. A

    Exploring Quantum Mechanics: A Thought Experiment Reveals Surprising Results

    I've been reading some cursory stuff about quantum mechanics, and I want to understand it better - so I have a little thought experiment that I'm curious about. Let's say there are two rooms that are connected by a thin wall with no window. A person is told to stand in one of the rooms for a...
  25. G

    B Exploring Double Slit Experiment in Space

    I was wondering if the double slit experiment had been conducted in space away from interference from Earth's magnetic core/field. I know the scientific community would have considered all variables and would have set proper controls for this experiment but I am unable to find any notes on this...
  26. Cygnus_A

    Relativity Prereq for Will: Theory and Experiment in Gravitational Phys

    Hi, I'm wondering how much prior knowledge I would need to get a lot out of this book. I'm considering taking an undergraduate General Relativity course next semester to help me learn parts of this book. I have some basic experience with curvilinear coords/tensor analysis along with a brief...
  27. I

    Correlation Between pH & Electrolysis Rate

    Hi, I have been performing an experiment to determine whether there is any correlation between pH and the rate of electrolysis. I have performed it using monobasic, dibasic and tribasic acids of constant concentration. However, I can't seem to find any correlation. Is there something I should...
  28. Stephanus

    Train Experiment Problem: Solve Derailment Mystery!

    Dear PF forum, I have a problem with Train experiment. Perhaps someone can take a look at it and tell me where did I go wrong? V = 0.6c; Gamma = 1.25 Train length = 1500 Platform length = 1200, so the light can reach the observer at the same time. I draw the space diagram for that problem...
  29. M

    Double slit experiment and mirrors

    Has the double slit experiment ever been performed with an adjacent reflection? With quantum weirdness I'm curious as to whether the reflection would give the same results as the actual apparatus as to which slit the particle wen through.
  30. M

    Double slit experiment - bias towards normal pattern?

    WARNING. I'm not a physicist! If there was a universe that only had 10000 photons and we observed all of them then ran the double slit experiment would we get a normal pattern or an interference pattern? If we observe a particle is that it forever in the universe that we happen to be running...
  31. jk22

    Measurement operator for Chsh experiment

    The experiment is described at p26 of http://arxiv.org/abs/quant-ph/0402001 In this experiment we see that we sum measurement results and not measure the sum. Is then the quantum measurement operator not : $$S=A\otimes B\otimes\mathbb{1_{64}}-\mathbb{1_{4}}\otimes A\otimes...
  32. J

    Can We Track a Photon's Path in the Double Slit Experiment?

    The results of the double slit experiment lead to the conclusion that a photon travels as a wave. Question 1: Is it possible to track the journey of the photon? It seems to me (correct me if I'm wrong) that from the moment we release the photon till contact with the detector we don't know what...
  33. olgerm

    Can an experiment demonstrate the existence of a gravitomagnetic field?

    I have thought about an experiment which to demostrate gravitomagntism: spinning massive cylinder creates gravitomagnetic field above it. Oscillating pendulum above the cylinder departs from its trajectory because of "gravito-Lorents" force. To calculate magnetic force above the cylinder I use...
  34. N

    Errors in basic current balance experiment?

    Hi guys, so I'm having a little trouble completing my physics lab report here due to not being able to find many errors to discuss about. The experiment that I conducted makes use of a basic current balance: http://www.pasco.com/prodCatalog/SF/SF-8607_basic-current-balance/ As you all know...
  35. M

    Where can I get Casimir plates?

    Where can I find actual Casimir plates? To buy or hire for experiments, I mean. If so, what do they cost?
  36. Splizard

    Double slit experiment with 2 detectors

    Can someone please point me to an experiment (photons/electrons/whatever) where detectors were placed on both slits, this seems like a really big hole in the experiment if they stopped at having just the one detector. (Excuse the pun)
  37. K

    Fizeau's Exp: Calculating Speed of Light w/ Red Laser

    Homework Statement Angular Speed of the 8 gap wheel Is variable. Red Laser (wavelength around 656.6 nm) Approximate the length of the traveling ray to the mirror in meters. Using the length of the traveling ray, calculate the speed of light. Homework Equations c=lambda*f The Attempt at a...
  38. A

    MHB Interference in a Double-Slit Experiment

    In a double-slit experiment, the distance between slits is 5.0mm and the slits are 1.0m from the screen. Two interference patterns can be seen on the screen: one due to light of wavelength 480nm, and the other due to light of wavelength 600nm. What is the separation on the screen between the...
  39. 0

    Energy and Momentum Thought Experiment

    Suppose two balls A and B are connected by a compressed massless spring initially, and they are not under any other forces. The spring is then released and the result is observed. Scenario 1: Ball A has the same mass as Ball B. Scenario 2: Ball A has greater mass than Ball B. Define the...
  40. G

    Indivisible units of time and the quantum eraser experiment

    If we take an indivisible unit of time (a Planck time perhaps), could the possible retro-causality hinted at in the Quantum Eraser Experiment be a process where the retro-causality goes back along the same plank unit rather than back in time per se Metaphor - I don't travel to a different train...
  41. S

    Could this experiment prove special relativity to be wrong?

    Think about an electric charged object moves linely, it will produce current hence the magnetic field. But if the obserser moves together with the electron charged object, so there is no relative movement between them, that means the electric charged object is static to the observer, hence...
  42. D

    Electron double slit experiment

    Is there an electric or magnetic field from the electron present in the deconstructive regions of the electron interference pattern?
  43. S

    Is the Delayed Choice Experiment Defining Our Understanding of Time?

    A Delayed Choice Experiment: Sorry, could not resist!
  44. aladinlamp

    Can a Sealed Device Increase Weight Continuously in the Direction of Gravity?

    Imagine red box as a fully enclosed device powered by electricity when turned off, it weighs 5kg, it is pushing down with force cca 49 Newtons when turned on, it would weight more, let's say 6kg, pushing down with force cca 58.86 Newtons is it in theory possible to make such device...
  45. Justice Hunter

    Does Dark Matter Interact with Itself in Black Holes?

    Hey so i have a naive question that i always had since i was young, but i never really could find an answer to it. Lets say you have a black hole isolated in a vacuum, in a closed system. Dark matter is supposed to be a sort of weakly interacting massive particle, which exerts a gravitational...
  46. H

    Did the experiment, now more confused

    some time ago I posted a question re acceleration data. I bought an accelerometer and logged some data. when stationary the accelerometer (can mention the brand if that is not spamming) read 1g, when thrown in the air got what was expected with 0g ie weightless when the accelerometer switched...
  47. arpon

    Finding value of constants of quadric equation by experiment

    Homework Statement Suppose, the following equation describes the relation between an independent and a dependent variable physical quantities(that will be measured by experiments; for example, temperature, current, voltage etc) x & y : ##y = ax^2 + bx + c## We have to find the values of the...
  48. T

    How can you actually measure the electron position?

    Standard quantum mechanics text-books discusses Born rule, which states that the probability of finding a particle in a certain region in space is given by $$ |\Psi ({\bf r},t)|^2d^3r $$ Thing is, I never have seen a discussion about how you can actually measure the particle position in a...
  49. DaveC426913

    Delayed choice experiment article on science alert

    I'm familiar with the delayed choice experiment, and I'm trying to suss out this new setup. http://www.sciencealert.com/reality-doesn-t-exist-until-we-measure-it-quantum-experiment-confirms Reading this article is not very beneficial if there's a confounding typo. Paragraph 10: Should that...
  50. A

    Can Virtual Particles Be Observed in Experiments?

    Hi guys i don't know much about physics but I am interested in learning about it i have According to wikipedia virtual particle hasnt never been observed but i think that they are wrong it has been observed in this experiment...
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