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. J

    Higgs Experiment for new particle (decay widths)

    < Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > Question: An experiment is proposed to directly measure the width (Γ) and mass (m_H) of the Higgs boson via the reaction: muon+ + muon- > H. Sketch a graph of the expected cross section as a...
  2. P

    Single photon and double slit experiment

    hi are the path lengths to the slits strictly equal? If the difference of the path lengths is progressively increased, how evolve the fringes visibility?
  3. M

    Helmholtz synthesizer experiment

    Hello all! Inspired by the Helmholtz synthesizer, I am experimenting with electromagnetic excitation and tuning forks. http://www.sites.hps.cam.ac.uk/whipple/explore/acoustics/hermanvonhelmholtz/helmholtzssynthesizer/ How can I determine the size and charge of an electromagnet in order to...
  4. T

    Eddy Current Speedometer Experiment

    Trying to create an experiment that utilizes a motor driven shaft to measure the angular velocity of another shaft via eddy currents. We made a mock experiment that uses 8mm shafts, pillow bearings, and ceramic magnets from home depot, but don't see a torque on a non-ferrous metal attached to a...
  5. S

    Young's double slit experiment green laser

    Homework Statement If a green laser is (wavelength = 532nm) sent through two slits with a separation of 127 um, how wide (in total) would the 11 green dots formed be if they were projected onto a screen 1.25m away from the slits? Refer to this diagram sorry for bad quality...
  6. M

    I Regarding Joule's gas expansion experiment

    Hi, Joule's original gas expansion experiment is often presented like in the following link: http://demonstrations.wolfram.com/JouleExperimentOnFreeExpansion/ The apparent lack of temperature change in this experiment is often used in textbooks to demonstrate that the energy of an ideal gas is...
  7. Z

    B Feynman experiment with bullets

    Hello, I have a question. In Feynman lectures vol. I, in chapter 37-2, Feynman has an experiment with bullets. *Copyright http://www.feynmanlectures.caltech.edu/III_01.html But the curve for ##P_{12}## looks in the picture is different from his live recorded lectures. *YouTube - Is the...
  8. Felipe Prado

    I Fizeau's Exp: TRANSFORMING VELOCITIES to Explain

    In 1851 Fizeau made a famous experiment which corroborated de Fresnel's drag coefficient of the luminiferous ether. In the experiment two light beams traveled through a tube of moving water (at 7cm per second), one moving against the water flow (let's called it beam A), and one for the water...
  9. K

    I Experiment Ideas using an MRI scanner?

    So I've stumbled upon a really cool opportunity this summer, where I basically have a hospital which has agreed to let me do an experiment using their 3T MRI machine. I'm a physics undergrad and I want to do a physics experiment using the MRI, but I have absolutely no idea what to do. I've tried...
  10. MatthijsRog

    I Fitting a curve over noisy data

    Hi all, I performed a resonance experiment over the past two weeks, in which I collected the intensity of a Fabry-Perot cavity whilst adjusting the mirror distance with a piezo-element (the specific setup of the experiment is fairly detached from the question I will ask). My raw data is...
  11. AbhiJeet Patil

    Instantaneous Speed of Gravity Experiment

    I n ordinary weighing scale, in left pan, there is spiral shaped coil (like that mosquito coil) or any long shaped rod. Middle point of this coil is touching the left pan. Let mass of this coil be W1. Second body of mass W2 is attached to other end of this coil. So the left pan is experiencing...
  12. slow

    B Can Antiparticle Collisions Occur Without Charge Intervention?

    One sometimes gets excited about something and loses sight of essential details, which when taken into account derail the attempt. If in this case that happens, I beg you to let me know. Is the next. Think of the mutual collision of a particle and its antiparticle. Before the collision there...
  13. physea

    2^k factorial experiment design

    Hello! In this webpage: https://onlinecourses.science.psu.edu/stat503/node/35 it describes the 2^k factorial experiment design. I understand that k is the number of factors that we are investigating (in this case two, a and b), 2 are the levels of each factor (+/-) and 2^k=4 is the number of...
  14. D

    I Tail in data of Duane-Hunt limit experiment

    https://photos-5.dropbox.com/t/2/AAC1PAsxThHE7dTxxumANssxIDSrZGA0wi9u1T2alieA9g/12/217355121/png/32x32/1/_/1/2/Screen%20Shot%202018-04-24%20at%2014.40.53.png/EJ6fyaMBGOQEIAIoAg/zVJasOZ8quUZpWc6eN6tzuO7YSmC-VjpQ4ikXIkpC8A?preserve_transparency=1&size=2048x1536&size_mode=3 So in looking at the...
  15. Clara Chung

    I Question about Powder X-ray diffraction experiment

    I don’t understand why do we use power in this experiment. If we use powder, the d spacings of each crystalline will be oriented randomly, why won’t the angle of reflection changes? I don’t understand the idea of using powder in the experiment. Thank you so much
  16. Q

    B A view of the double-slit experiment

    Greetings. My name is Antti, I'm from Finland. My scientific background consists mostly if not only from watching youtube videos about science and Googling things that I'm curious about. So i registered on this forum to ask questions from the more educated people. So here's my understanding as...
  17. G

    B FTL train + FTL communication thought experiment

    Please move this if it belongs to other subforums. So i thought about some other stuff and then somehow this idea appeared to me, now according to physics it is impossible to communicate information faster than the speed of light through vacuum which is "c". So for any two bodies moving in...
  18. ohwilleke

    I What false hints of new physics were most notable?

    Sometimes experimental or observational evidence from credible physicists points to new physics and then turns out to be wrong due to statistical flukes, experimental error or a theoretical analysis mistake. What cases of this happening do you find most notable, what showed that the hints were...
  19. Dustin

    B 4 Questions About Lenz's Law Experiment

    Hello, I have four questions. As it stands now, I don't have the necessary materials to test this myself, which is how I'd prefer to learn the answer. I still plan on doing this experiment for fun once I can acquire the necessary components. This deals with Lenz's Law. My goal is to maximize...
  20. M

    Inteference Fringes of Double Slit Experiment in Water

    Homework Statement Suppose a double-slit experiment is immersed in water (with an index of refraction of 1.33). When in the water, what happens to the interference fringes? Homework Equations λ = λ0 / n y = (λmL) / d d = distance between slits L = distance to viewing screen n = index of...
  21. D

    B Different size slits in Young's double slit experiment

    Hi all I was wondering what happens if one slit in youngs double slit is bigger than the other? I recon that the of maxima will rise and in minima, there will be no dark spot, but dim light instead. Is that correct? If not can you please explain what happens? Thanks
  22. mfb

    I A proposed experiment to test quantum gravity

    Gravity is weak - while we can study the other interactions with individual particles, for gravity we need macroscopic objects to get measurable forces. This makes it easy to measure quantum effects for the other interactions, but hard to do so with gravity. Gravitational forces are always...
  23. F

    I What causes the formation of multiple sub-beams in the Stern Gerlach Experiment?

    Hello Everyone, I am reviewing the SG experiment. I think the experiment was set out to demonstrate that the orbital angular momentum ##L## is quantized producing a quantized magnetic momentum. But silver and hydrogen atoms have no net orbital angular momentum. Still two sub-beams, due to two...
  24. B

    Parallel Axis Theorem Experiment

    Homework Statement I am currently working on a physics experiment to confirm the parallel axis theorem. To do this, I have the following setup: In this experiment I change the distance between the centre of the rotating disc and the central axis. I record the time for 5 complete rotations...
  25. M

    Sources of Error in a Speed of Sound Experiment

    Homework Statement Determine sources of error which could have affected the results. Some background information: The lab consisted of playing a tone generated by a tone generator above a standing open-closed tube which had water in it. The first harmonic was measured through a computer system...
  26. CricK0es

    Uncertainty of a chosen value

    Homework Statement I have taken 5 sets of readings of voltage against angle for an experiment to determine specific rotation. (I'm using the maxima to determine the phase shift) So, having averaged these values and determined the maximum, I can then trace back to the angle at which this...
  27. K

    I Thought experiment: Photons in a box

    Consider a box whose walls are mirrors. Suppose we trap a bunch (yes, it's vague) of photons inside the box. They will not escape, or assume that a major part of them will not escape the box. Now suppose we have a way of decreasing the size of the box at our will, but possibly obeying the laws...
  28. PumpkinCougar95

    B Young's Double slit experiment with different slit sizes

    What would happen if a youngs double slit experiment is done with different slit sizes? I get the feeling that the intensity might never be zero as the waves might never cancel out completely. Am I right? How should I analyse the Intensity? Would I have to do something like what is done while...
  29. Mentz114

    I Beam splitter in an entanglement swapping experiment

    I have a misunderstanding about the beam splitter in this experiment High fidelity entanglement swapping with fully independent sources Rainer Kaltenbaek, Robert Prevedel, Markus Aspelmeyer,Anton Zeilinger http://arxiv.org/pdf/0809.3991.pdf Part of the diagram is reproduced here Two photons...
  30. R

    Error calculation for µ in standing wave experiment

    Homework Statement I experimented with standing waves on an oscillating string, and I was asked to calculate the absolute error of µ (linear mass per unit length). I don't know how to calculate it, so please help me. I loaded 100g, 200g and 300g on the string. Below are tabulated data of the...
  31. Y

    Forces involved in egg-drop experiment: 25 Newtons to Break an Egg?

    Homework Statement So I've spent many hours on here and deep deeeeeep in my textbooks trying to learn things...that pertain to the Egg drop experiment I am almost done with everything I need but I was wondering. I've read that it takes approximately 25 Newtons of force to break an...
  32. Sandeep T S

    B Einstein's Lift Experiment: Unlocking the Principle of Equivalence

    In Principle of equivalence, we indroduce to the theoram by a lift experiment, my question is why the lift is fully closed one, why the observer in lift forbidden to observe out side world
  33. Physics345

    Thomas Young's double slit experiment

    Homework Statement a) Explain why a pattern of bright and dark fringes visible on a screen when a light is shone through a double slit. b) Upon using Thomas Young's double-slit experiment to obtain measurements, the following data were obtained. use this data to determine the wavelength of...
  34. A

    Young's double slit experiment with two sets of slits

    1. The problem statement, all variables and given/known da Homework Equations Interference minima is asinΘ=nλ/2 where n=1,3,5,7... [/B]The Attempt at a Solution Putting ab/(2sqrt(b^2/4+d^2))=λ/2 for first order minima And solving for d I get (b/2)*sqrt((2a/λ)^2-1) in which only the 2 factor...
  35. Lukeblackhill

    Galileo's Experiment with an Inclined Plane

    Morning mates, I've peformed Galileo's experiment with inclined planes, using a ramp of 88cm (divided in 4 parts of 22cm), inclined by a height on the right-edge of 4cm. I've measured the following, 1/4 of the ramp (22cm): 1.75s (error of 0.1s) 1/2 of the ramp (44cm): 2.70s (error of 0.1s) 3/4...
  36. J

    Magnetostatics experiment flowchart - How can I improve this

    Homework Statement I'm attempting to write a FORTRAN program that calcuates the magnetic field, B, at any point outside of a bar magnet. I will be using a simple first order euler scheme for numerical surface integration. Homework Equations Here is the exact method I will be using...
  37. A

    I Why do we need a theory to replace the Galilian composition of velocities?

    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...
  38. A

    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.
  39. SuchBants

    I Cavendish experiment to determine G

    I'm doing the experiment for a project using a setup as so: https://imgur.com/a/7vfg2 In the derivation of the formula I used the amplitude of the oscillation on the ruler of the laser, basically taking it as the arclength of the arc drawn by the laser spot as the bar rotates inside the...
  40. S

    B Delayed Choice Quantum Eraser Experiment Results

    Hello everyone. I want to ask some questions about dcqe experiments results which are bugging my mind. It is so hard to find reliable sources in my native language so I'm here. Also sorry for my scuffed english. Assuming we all know the famous experiment setup, I am directly passing to the...
  41. berkeman

    Looking for CFD simulation help on this Aero experiment

    Hoping to get some help on a stability analysis of this setup...
  42. K

    B Preserving causality in the EPR experiment

    I have previously posted Preserving local realism in the EPR experiment . I have since given up on simulating local realism since I now understand it is impossible. However I have not given up on causality. Attached is code that simulates the EPR experiment and gives the same result as what...
  43. F

    I Thought experiment about wave functions

    Suppose we have a particle, let's say an electron, in a box of size D. And we add another one next to it at some distance L center to center. How do we solve for the wavefunctions of the electron. Can it be solved in normal QM or do we need QFT. Thanks.
  44. T

    Gyroscope Experiment Homework: Find Centre of Gravity & Nutation Effects

    Homework Statement Ok so in my lab we have been given a set-up as shown below Minus the horse shoe dector on the right hand side. During this set-up up we need to find the point where the balance point and centre of gravity are equal (as I understand) here is exactly what my script say...
  45. W

    I Spin confusion: Stern-Gerlach experiment

    I have some serious issues trying to understand the idea of the spin in the context of the Stern-Gerlach experiment and would appreciate some assistance! Assuming that a homogenous magnetic field ##B## in the "North-wards" ##z##-direction, assume that there is a magnetic dipole moment ##\mu##...
  46. M

    Thought experiment - water at the bottom of the sea

    So as we know at the bottom of the ocean we have water cooled to 0-4 degrees celsius which is very dense and also compressed due to the pressure. Imagine we lower a few kilometres long pipe to the bottom of the ocean (it's made of material that is strong enough to sustain pressure). It's closed...
  47. tinocasals

    Nuclear physics interesting experiments and activities

    Hi there, I'm looking for some interesting activities regarding nuclear physics in high school. I already have: - building a cloud chamber with dry ice or peltier modules - simulating radioactive decay with dice - simulating Rutherford's experiment hitting with glass marbles a hidden target...
  48. M

    B Unusual question about video experiment on YouTube

    Hello, I have found a YT video which shows some kind of experiment. You see a wooden toothpick suspended on a spider's web single thread and covered by a jar. Then a you see a man who holds a few plastic straws in his hand. He closes them to the toothpick and it slowly moves (which is seen if...
  49. S

    I Davison-Germer experiment - Bragg condition

    Hey, I'm trying to adapt the Bragg condition for the David-Germer experiment, so I can then use their experimental results to show that the measured wavelength is compatible to the wavelength theorized by De Broglie. However I'm having issue with the calculation, any help would be much...
  50. J

    Experiment to determine the time period of a pendulum

    Homework Statement Homework EquationsThe Attempt at a Solution Time period of a simple pendulum is given by 2π√(L/g) . By uniform mass distribution , I am assuming density of mass of bob to be constant . I don't understand how time period depends on the mass of the bob of a simple pendulum .
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