What is Experiment: Definition and 1000 Discussions

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. Jim Lundquist

    Thought Experiment on the Dual Nature of EM Radiation

    The following question/thought experiment is based on the dual nature (particle/wave) of electromagnetic radiation. Consider the emisson of a single photon on a 3D grid along the x-axis with its origin at (0,0,0). The only matter in this experiment consists of “electrons” found only in...
  2. kamhogo

    Double-slit experiment: What is the speed of the neutrons?

    Homework Statement An experiment was performed in which neutrons were shot through two slits spaced 0.10 mm apart and detected 3.5 m behind the slits. The following figure shows the detector output. Notice the 100 μm scale on the figure. To two significant figures, what was the speed of the...
  3. Dadface

    I Birgit Dopfer interference experiment

    Hello. I'm interested in the experimental details of the above and have found what I believe to be the original published write up of the experiment. The document is in German and I have managed to get a reasonable understanding of the details mainly from the diagrams and graphs. Translation is...
  4. entropy1

    Interpretation of polarisation experiment

    Consider a fully entangled pair of polarized photons, A and B, fired at two detectors with polarisation filters in front of them. I have to get a little philosophical to understand the way the interpretations of this experiment play out. My knowledge is still very basic but I'm working on it...
  5. O

    Ferromagnetism - thought problem

    Hi! This might be a dum idea but here goes. Say you have 3 items. One weak magnet and two ferromagnetic materials of different susceptability. The magnet is strong enough to saturate the first material bot not the second. But since the saturated field in the first material is larger than that...
  6. Davephaelon

    B Golf Ball in Flat Space-Time: Return or Shift?

    Imagine a test particle (say a golf ball) just floating in flat space-time. Now have a sunlike star instantly appear some distance away. From the perspective of a distant observer, (using very distant background stars for reference), the golf ball will be shifted towards the star a certain...
  7. ZawL

    I Clock Thought Exp: A Light-Year Time Paradox

    This is a thought experiment I came up with this evening. It must surely have been considered before but I couldn't find any reference and I've come up with it independently. NASA has positioned a clock in Earth's thermosphere that can be viewed from outer space with a powerful enough telescope...
  8. B

    Double-Slit Experiment problem?

    Homework Statement In a double-slit experiment, the third order bright fringe is 15 mm from the central fringe. What is the distance of the first (zero-th order) dark fringe from the central maximum? Homework Equations (m+.5)(lambda) = dsin(theta) => dark fringe m(lambda) = dsin(theta) =>...
  9. K

    Schools Faraday rotation experiment for a high school student?

    Is it possible to replicate the Faraday rotation experiment for a high school junior? I am in honors physics (IB) and have been taught about waves, electromagnetism, energy transfers, etc. My physics teacher will guide me if I choose to do this. Is the experiment too ambitious?
  10. L

    A Compare absorption spectra from calculation and experiment

    hi pf nice to see you. I have a question about optical absorption spectrum of nanoscale substrates. To get an absorption spectrum of nanostrucutred material, I want to perform both fdtd calculation and optical simulation. When I do fdtd calculation, I set the incident light illuminated with...
  11. B

    I Lab experiment: hysteresis disappears, reappears and then disappears again. How?

    Hi people, In my college laboratory we were assigned an experiment to measure the hysteresis curves of a certain ferromagnetic material at different temperatures. Sounds simple, right? Well, the block of Monel 400 we chose did something weird. We cooled it down to about -200°C and set about to...
  12. I

    B Finding a Gas for Physics Experiment

    Hello I am currently performing an interesting physics experiment and am in need of a gas that is easily accessible and can easily be ionized by someone with basic equipment. Any help would be greatly appreciated.
  13. EnumaElish

    I (How) does the LIGO experiment falsify Newtonian gravity?

    Sorry for the amateurish setup that follows. Here's my thought experiment. Consider a 2-dimensional universe on the Cartesian plane. Earth is located at point (0,0). There is a binary system {A,B} oscillating around (1,1). To simplify, assume that the oscillation is 1-dimensional and occurs on...
  14. B

    NASA's experiment with a gyroscope featured in Fabric of the Cosmos

    In Brian Greene's documentary The Fabric of the Cosmos, the thesis of the documentary is that empty space has physical properties even if there are no atoms or molecules in it. As I recall, most of the documentary shows the story of how NASA had a goal of sending a gyroscope up into space to...
  15. A

    A What is the correct reply on Einstein`s thought experiment?

    In attempt to refute quantum mechanics, Einstein proposed a thought experiment where a box containing a particle is weighted before and after opening a small hole to release that particle. The precision of measuring the time and the energy of the particle can thus be known accurately which...
  16. Chezz42

    In my experiment on transformers, the data showed

    So I did an experiment a this week on the relationship between two tightly wrapped coils with same length and number of coils in a transformer. This was in a compete circuit using AC currents. I measured the Voltage, keeping the currents the same. One experiment had an iron core between the two...
  17. VonNathan

    Experiment to measure frequency of de Broglie waves

    Homework Statement Somebody knows an experiment to measure directly frequency of de Broglie waves?
  18. D

    I Determination of electron energy in the 2 slit experiment

    If w3e fire electrons thru the 2 slit we get an interference pattern showing the wave nature of the electron. Now if we cover one of the slits and fire electrons we get a bar like pattern on the screen. If we cover one slit, fire electrons and use a detector we would also get a bar like...
  19. NeedHelpBro

    I A.P French equation Question -- singing wine glass experiment

    Hi, I have been researching about the singing wine glass experiment (EEI). I was wondering where i could find more research papers or information about this equation. I was also wondering what the equation in finding the constant (beta). Thanks,
  20. kenok1216

    What is the Newtion Ring Experiment?

    Homework Statement refractive index of prism=1.45 λ=450nm 50 bright ring are observed find dHomework Equations 2d=nλ/2 The Attempt at a Solution since 50 bright rings are observed n=24 (-24---------0-------------24) if the distance travel=λ/2 constructive interference will happen since the...
  21. T

    Finding centripedal acceleration with tangential acceleration

    Homework Statement I'm trying to find the centripedal acceleration of a roller coaster at a certain point in time from experimental data of acceleration in the X, Y, and Z directions. I do not know the velocity of the roller coaster, only the acceleration. Thank you! Homework Equations v^2/r...
  22. Waffuru

    B Need help to create an experiment

    Hi, my physics teacher ask us to create some experiment to be presented, related to the contents from the first year university course in physics. I would like to do something really unusual and interesting, however I don't have any idea. I would appreciate any suggestion. Thanks
  23. M

    Finding the Value of Acceleration Due to Gravity: Using Graphs and Equations

    Hello everyone, I did an experiment titled 'mass on a spiral spring' in order to find the value for the acceleration due to gravity. The experiment consists of two parts. In the first part of this experiment, I just measured the oscillation period of a spring as a suspended mass and plotted...
  24. T

    MHB What is the Probability of Getting Three Heads in 30 Coin Tosses?

    Conduct 30 trials and calculate emperical probability of the outcomes. What is the probability of tossing 1 coin three times and getting three heads? Need a flowchart of some sort to show all possible outcomes. This math is new to me and has little understanding of this math lol so any help...
  25. entropy1

    B Thought experiment violates Heisenberg? (of course not)

    Suppose we have an elementary double-slit experiment: A laser fires individual photons through a double slit at a detectionscreen made of atoms. As we fire photons, an interference pattern emerges, exposing the momentum of the photons (the frequency of the laser). So, we have registration of...
  26. Y

    Describe absorption experiment to distinguish 3 radiations

    Homework Statement I could not fit the whole problem typed out but; Describe with a diagram, an absorption experiment to distingush between alpha, beta and gamma radiation. Homework Equations None required, written question. The Attempt at a Solution Source, absorbers placed in front of...
  27. PhotonSSBM

    Justifying Ampere's Law and Faradays Law with an experiment

    Homework Statement Given Ampere's Law and Faraday's Law (in differential or integral form fwiw) explain why it is easier to design an experiment to show that a changing magnetic field creates an electric field than it is to show a changing electric field creates a magnetic field. Justify your...
  28. N

    Source of light in Michelson-Morley experiment

    Hi I wonder if anyone can tell me what was the source of light Michelson and Morley used when they did the experiment(s) to measure the (difference of) speed of light in different directions? And can it be done with sunlight? Young observed interference patterns with sunlight in 1801 in...
  29. Ken Gallock

    B What kind of experiment is needed to quantize gravity?

    Hi everyone. I heard that there are several theories or hypotheses to quantize gravity such as superstring theory, loop quantum gravity, etc., and I believe none of them are conclusive (that's what I heard). So, here is my question. 1) Is it because there are no experimental results which prove...
  30. C

    B LIGO experiment Gravity waves

    I read that they found gravity waves that have the frequency of 35 to 250 hz but are not these frequencies that of sound waves? I thought sound does not propagate in vacuum or is there a new kind of gravity vacuum that contains a gravity ether or dark matter?
  31. firefox

    Negative Moment of Inertia from Atwood Machine Experiment?

    I'm currently completing an Atwood Machine Experiment with two 100g weights on either side of the pulley, with a variance in weight created by attaching dimes and pennies to either side of the weights. The point of the experiment is to validate: (m1 – m2)g = (m1 + m2 + I/R2) Homework Statement...
  32. J

    I Light speed and the LIGO experiment

    Hello all, I was thinking about the speed of light and why it's constant and it brought me to the principle of the LIGO experiment for which I have an assumption that I want to verify. I'm a novice at this so please bear with me. From what I know, the LIGO experiment splits an emitting light...
  33. R

    B Ether and Michelson-Morley experiment

    why ether medium fail in michelson morley experiment?
  34. Newtonfalls

    Make Water Behave Like In Space -- Video

    Hi, just came across a video on CNN showing how to make water behave like it would in space: <link to video deleted> My question about that video is: what height do i need to get a free fall time of 10 sec? best regards
  35. K

    Interesting mechanics experiments

    Hello! I am new to this forum so I don't know if I am posting this under the right part. Anyway, I am an undergrad and my phys 101 mechanics course requires to come up with an experiment related to the course content, write a report on it and present it to TAs. I decided on a simple pendulum...
  36. L

    I Thought experiment: Communication beyond the particle horizon

    Refer to this image: http://imgur.com/xT20HOv The white nodes are 'stations' which broadcast signals at light speed. The blue circles around them represent the particle horizon relative to these nodes. The pink nodes are intermediary stations in between these stations that pass on the signal...
  37. H

    Simple experiment to measure resistance of a semiconductor

    Unlike Ohmic resistors the resistance of a semiconductor decreases with temperature...or not. Can a fragment chipped off a diode or some random IC be used to measure this with a multi meter??
  38. I

    B "Forced Conclusion" in Train-Embankment Experiment

    In the train-embankment thought experiment described by Einstein in his "public" version of STR, he says the following: “Hence the observer will see the beam of light emitted from B [the front of the train] earlier than he will see that emitted from A [the rear of the train]. Observers who take...
  39. nsaspook

    What happened to Microsoft's AI chatbot on Twitter?

    What happens when an innocent AI chatbot meets Twitter? NSFW language. http://www.telegraph.co.uk/technology/2016/03/24/microsofts-teen-girl-ai-turns-into-a-hitler-loving-sex-robot-wit/
  40. V

    B Turning Einstein’s train thought experiment on its head

    Let us first review Einstein’s train and platform thought experiment which consists of one observer midway inside a speeding train car and another observer standing on a platform as the train moves past. A flash of light is given off at the center of the train car just as the two observers pass...
  41. R

    I Experiment to test the basic assumption of SR

    Has there ever been an experiment to support the principle assumption of relativity? For example an experiment where an atomic clock is sent on a probe to , let's say, Pluto. We on Earth get transmissions of the time on that ship and, after taking account of the light travel time delay, we...
  42. secur

    I Dark Matter Detection Experiment Results?

    In 2011 Dr. Gerald Guralnik of Brown University was involved in an ongoing Dark Matter Detection experiment, perhaps LUX? It was an international collaboration involving underground detectors. He was certain DM would be detected in 5 years - i.e., now. I was dubious, so we bet "bragging rights"...
  43. G

    Experiment to find out emf of the battery

    I conducted an experiment to find out the emf of a battery, the result turned out to be 1.35 volts , however on the battery, it says the battery is 1.5 voltage. Does it mean that my method is wrong or less accurate. But I used three different methods:1) measuring the terminal voltage across...
  44. F

    Admissions Will HEP Experience Limit My Grad School Options in Theoretical Physics?

    Hi there, I'm a junior in undergrad, and so far I've had a summer of research experience at an REU, just started research at my current school in December, and am doing another REU this summer. I'm a transfer student and at my previous school there were literally no research opportunities...
  45. E

    B What is the Effect of Normal Lines on Glass Surfaces?

    I am a degree student and .. A loner. During my free time, I usually try to observe my surrounding more, you know... :\ Here's the experiment I did (I saved it in my note app, copied it directly from there): A certain window has a point of view (not referring to the meaning where point of view...
  46. M

    Rate of water flow experiment question

    Hi, I am mike from australia, I am new to the forums and am having trouble answering the question below, I have included some information on the experiment as well. You are given a water bottle with a pin sized hole in the bottom, and a line drawn around the bottle at the level that 50cm3 of...
  47. M

    B Einstein Train Experiment Consequence: Will Observer A be Shot?

    If we take a look at the experiment were two observers A (inside a train) and B on the platform observering the train as it pass by. Person A will stand in the exact middle of the train and send out a light wave. Person A will observe the light to hit the wall at the same time, while person two...
  48. Z

    Resonance frequency of a wine glass experiment

    Homework Statement My group and i need to do an experiment for school. We decided to investigate the effect of water level in a vine glass (or volume) on the resonance frequency. Basically does the resonance frequency change when you change add water to the glass. I would just like some help...
  49. tkmanutk

    I Special relativity thought experiment

    The subject of relativity has been haunting me for while now. Everytime i feel i understand a concept, there comes questions withtin that contradict the undestanding. Have been trying to digest the time dilation & symmetry of how it is felt mutually by observers in two different frame of...
  50. D

    B How Does the Double Slit Experiment Show Both Particle and Wave Behaviors?

    From my shallow understanding, when we shoot a small amount of electrons through the slits while observing, the observation interfere with the electrons and the quantum system and thus collapse the wave function, making the electrons behave like a particle and form a 2-slit pattern on the...
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