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. E

    Please help with this physics experiment -- Water leaking out of inverted water bottle

    Vc-volume of the water that came out Vall-volume of the water before leakage S-area of the glass bottle h-bottles high h1-height of air column before leakage h2-height of the air column after leakage hv,1-height of the water column before leakage hv,2-height of the water column after leakage...
  2. M

    I Experiment on the variation of weight with temperature

    Hello ! According to what I have read on the internet, the weight of a body varies with temperature, its mass remaining unchanged according to the theory of relativity. My question is what experiment is done to corroborate that the weight of a body increases with the increase in its...
  3. C

    I Have You Heard of the SEW Experiment? Thoughts?

    The SEW Experiment, named after its authors, Marian 0. Scully, Berthold-Georg Englert &Herbert Walther, was published in 1991 under the title, "Quantum optical tests of complementarity," and can be found here: https://www.nature.com/articles/351111a0.pdf They built atom interferometers with...
  4. C

    I How To Experimentally Confirm the Wigner-Von Neumann Interpretation

    Consider a simple quantum eraser setup using polarizers: An incident beam polarized at 45º is sent towards a double slit. After slit A there is a horizontal polarizer and after slit B there is a vertical polarizer. At the back screen, if we run this experiment, we will see a particle pattern and...
  5. P

    Modelling the voltage measured across a dc motor

    Hi there, I have done an experiment measuring the voltage across the terminals of a dc motor, whilst running and then by holding it with my fingers to stop it. Done as demo for my high school class. The voltage reading was higher when the motor was running, which was against my expectations as...
  6. P

    How should this Beam Loading experiment be designed?

    The question and my attempt at a solution are attached. Thanks.
  7. Steve Rogers

    A water-bottle demonstration of atmospheric pressure

    I'd like to ask about an experiment on atmospheric pressure. To conduct the experiment, we need an empty PET bottle and make a small cut on the lower part of the bottle. A cut no greater than one-half the circumference is acceptable. Then, we press a table tennis ball against the cut to open the...
  8. S

    I Calculation of temperature changes (heating a cube in a microwave oven)

    Hello guys, I am currently running an experiment in my hobby room: I want to heat a cube in a microwave and then measure the surface temperature. Unfortunately, it takes about 20 seconds, so the cube cools down during this time which means I don't measure the actual temperature after heating...
  9. srnixo

    Understanding Time Measurement in Physics: Uncertainty and Calculations

    So as you can see in the image, I have noted the time in the [time column (s) ] on the table after conducting the experiment at home using the application phyphox. And now, I have some questions to fill in the remaining gaps: The first question: about ΔH (m) : Should I set it equal to zero...
  10. J

    I How to improve the accuracy of Young's double slit experiment?

    My teacher asked me to find the separation of a double slit by finding the distance between fringes. I wonder how I can reduce the experiment error. So what can I do?
  11. R

    I Advice regarding sled experiment

    Hello. I would like to design an experiment where different sled designs are compared. Specifically, I would like to asses how sled design affects the amount of force required to pull a sled over 100 meters. Any suggestions you might have would be greatly appreciated.
  12. SCHROEDERFPM

    I Looking for knowledge and insight about Magnetohydrodynamics and a simple setup to observe the phenomenon

    I have been reading about Magnetohydrodynamics and would like a bit of insight from anyone who has any knowledge on the subject. If I understand correctly when a conductive fluid is in motion it produces an electric field, and motion can be generated using a few methods one of which is a...
  13. mahdis

    Flow rate experiment not producing same results as the Hagen-Poiseuille law?

    I have repeated the experiment several times and it always shows my longer length has the fastest flow rate. the same results occur when I apply 300mmH pressure to the fluid bag on top, the flow rate is still faster in the longer pipe
  14. Sciencemaster

    Misc. DIY Experiment of Special Relativistic Effects?

    I'd like to perform an experiment that will build intuition for Special Relativity in the real world. While I do believe that it occurs in the real world, I'd like to be able to prove it for myself, and I feel that such an experiment would help others on this forum as well. Is there an...
  15. S

    I Question about an interesting experiment video (two magnetic balls in tubes)

    In this video... https://www.physicsforums.com/media/magic-magnetic-balls-defy-physics.6951/ ... a pair of magnetic balls in two vertical tubes, roll upwards when the tubes are rotated, irrespective of the direction you rotate them in. A couple of questions... [1] Say the tubes are mounted...
  16. James_AA

    I Laser and nano-holes experiment

    Hi everyone, let me propose an experiment to see if you agree with my points. There is a 1cm2 1-micron thick aluminum substrate with a matrix of 100x100 nano-holes each with 100x100nanometers cross section separated by 100nanometers. Then, we focus a 1W laser with visible wavelength: 1-...
  17. A

    I Simultaneity and Reality: Construct a thought experiment similar to this one described by Einstein

    I want to construct an experiment similar to that described by Einstein in his thought experiment: https://en.wikisource.org/wiki/Relativity:_The_Special_and_General_Theory/Part_I#Section_9_-_The_Relativity_of_Simultaneity How would I design it to ensure the light from the flashes at the back...
  18. T

    I Quantum behavior experiment flawed?

    I would like to discuss this experiment, could it be flawed?: http://people.whitman.edu/~beckmk/QM/grangier/Thorn_ajp.pdf Let's start here with another setup: In the video it's shown that the field is continuous and splits 50/50 at the beam splitter, no matter how much it's attenuated. Also...
  19. PhysicsRock

    Estimating Error in Wavelength from Graphical Approach

    As part of my studies, I'm obliged to take an experimental course at the moment, where I have to conduct experiments and write a composition. Today we examined spectral lines of helium with a prism. As part of the evaluation, I had to plot the measured diffraction angles of different colors /...
  20. V

    Verification of ideal gas law experiment

    TL;DR Summary: I measured the mass of CO2. Can someone verify my calculations? I took a soda bottle and filled it with Carbon Dioxide then weighted its mass as I changed pressures. My figures get very close (5-10%) within the calculated values for psig but not psi-absolute. Can someone confirm...
  21. K

    I How experimentally robust is Giant Dipole Resonance in 88Be?

    I saw this paper, Observation of the X17 anomaly in the decay of the Giant Dipole Resonance of 88Be 2308.06473 I would like to know how robust and how established is experiments involving on Giant Dipole Resonance How easy would another research team to use on Giant Dipole Resonance...
  22. gxa

    Real Experiment-MCBEND Simulation

    Do I need to apply normalization these two graphs to make them similar to each other and if so, how can I do this? I would be very grateful if you can help me if these results are consistent. I compared the results of the experiment and the results of the mcbend simulation.
  23. Entropix

    I Hydrogen balloon experiment -- How high can it rise?

    If we launch a hydrogen balloon from the Earth surface (let's say it has a 2 meter radius) and assuming it's strong enough so it doesn't pop/disintegrate (it's made out of carbon nano-tubes). Where this balloon will stop? I'm more interested in the exact altitude it reaches or if it will keep...
  24. Salmone

    How is an autocorrelation function computed? (Dynamic Light Scattering)

    In an experiment of Dynamic Light Scattering, how is an autocorrelation like the one in the image computed? Mathematically a correlation function can be written as ##G(\tau)=\langle I(t)I(t+\tau) \rangle##, in an experiment like the one I mentioned the scattered intensity light is collected by...
  25. M

    Instrumentation Amplifier for Wheatstone Bridge Output

    I am going to do some experiment on mechanical mechanism , studying stresses Thing that in my mind Arduino Strain gauge Instrumentation amplifier I want to know that which Instrumentation amplifier i should use to get good output voltage from wheatstone bridge circuit and also easy to use...
  26. new_scientist

    I Is the energy destroyed in this experiment?

    Suppose you stand on a spherical permanent magnet in space and you hold an iron ball in your hand, you can neglect the gravity force by this magnet mass. You stand and throw the iron ball upwards with some kinetic energy, the ball will eventually stops at some height because it is attracted by...
  27. Q

    Physics IA: Distance B/w Pendulum & Alum. Block, Finding Damping Coefficient

    TL;DR Summary: I am doing an experiment for my Physics IA and don't know the theory behind it I am working on a Physics experiment for my school where I vary the distance between a simple pendulum and an aluminium block, and get the damping coefficient for each distance. Below are the images...
  28. M

    What are some fun permanent magnet experiments for kids?

    Howdy. My kids and I like to experiment with things, we're looking to play around with some permanent magnet experiments and when I googled a question it brought me here, so I figured, heck, might be able to get my questions answered as well :)
  29. Grelbr42

    I Unlocking the Potential of Back-to-Back Photons: an Experiment

    In some cases, photons can be produced in "back to back" (BTB) conditions. For example, electron-positron annihilation produces two photons, each at 0.511 MeV, with equal and opposite momentum. Or pretty close, up to the original velocities of the electron and positron. Start with a source of...
  30. hyksos

    I Exploring the Casimir Effect: The Archimedes Experiment

    Vacuum energy is predicted by Quantum Field Theory, and also independently corroborated by recent observations in cosmology involving accelerated expansion. More corroboration occurs in superconducting cuprates exhibiting quantum criticality, and in the Casimir effect The island of Sardinia...
  31. S

    Experiment about diode related to temperature and potential difference

    (a) I know some of the apparatus needed for the experiment, such as DC power supply, ammeter, voltmeter, maybe rheostat. But I don't know how to change the temperature of diode. What is the correct and safe way to change the temperature of diode? Thanks
  32. B

    I Faraday's Nested Sphere Experiment

    Hi there! I have a question about the Faraday's Nested Sphere Experiment, please see the attached pdf. I wonder why equation (1) and the electric field's equation ( coming after (1) ) consider only the charge Q. Why there aren't charge -Q in the equation? Ps. I'm thinking about point charges...
  33. sbrothy

    I Classic 'Double-Slit' Experiment Using Time Instead of Space

    (Not sure about the prefix. Choose intermediate to be sure.) This article Physicists Recreate Classic 'Double-Slit' Experiment Using Time Instead of Space has it's basis in this paper: Double-slit time diffraction at optical frequencies It certainly sounds intriguing but is there actually...
  34. Astronuc

    I Experiment finds gluon mass in the proton (?)

    Article published at Phys.org - Experiment finds gluon mass in the proton https://phys.org/news/2023-03-gluon-mass-proton.html An interesting diagram accompanies the article. Article in Nature (requires subscription or purchase, but one can read the abstract)...
  35. Addez123

    B What is causing destructive interference in double slit experiment?

    When you do the double slit experiment with photons or electrons you get a wave pattern. At certain points no electrons are detected. This is said to be caused by destructive interference. Destructive interference of what? If we shoot single electrons, one at a time, from where is this...
  36. K

    B Simple yet effective way to reliably control the DC Motor speed?

    As a part of our physics high-school self-study, we are making a stroboscope. We have a small 5-V DC motor that powers the strobe disk. It works as expected, but, clearly, the motor makes the disk spin at a constant speed. Is there an easy, but effective and reliable way to control its speed...
  37. K

    B Searching for Quantum Mechanics Lecture on Delayed Choice Experiment

    Hi everybody. Some years ago I came across a video on youtube where they talked about an experiment with small and large envelops, when the small ones were placed into the large ones and then it resulted in something interesting. It might have been an instance of delayed choice, but I am not...
  38. J

    I Observer effect in the Dual Slit experiment

    How detectors/observers in front of each slit works , does it somehow disturb with electron/photon? Does photon/electron must pass through detector/observer, so maybe his internal parts change final result on screen into just two lines?
  39. C

    A Two Slit Interference Experiment Variations

    Examples that have references to special two slit experiments : https://sciencedemonstrations.fas.harvard.edu/presentations/single-photon-interference https://en.wikipedia.org/wiki/Double-slit_experiment If you have an opinion on what you think the experiments tend to support and what they do...
  40. S

    I William Herschel's light experiment

    In Cosmos: A Spacetime Odyssey episode 5 Hiding in the Light, Neil Degrasse Tyson describes one of William Herschel's experiments with light in the year 1800. The episode shows Herschel's experiment as a cartoon. Herschel put two thermometers under a prism that was in the sunlight. Herschel put...
  41. C

    B A thought experiment of the relativity of light

    A light source in uniform motion emits a flash of light. A spherically symmetric wavefront propagates from a central point, the source, or the “origin” of emission. The wave front remains at c relative to the origin as measured by all observers. How fast do these origins move? Am I missing...
  42. V

    I How to rule out that the speed of light was different in the past?

    The constancy of the speed of light is a fundamental principle in modern physics, and it is supported by a wide range of current experimental evidence. There is no evidence to suggest that the speed of light was different in the past, and the idea that it could have been different is at odds...
  43. Beekeeper

    I Sonoluminescence experiment -- help please

    Hi, I am working on a sonoluminescence experiment and am having trouble with it. The problem is that although I can trap a bubble, I cannot get it to glow. I am following the same procedure described by 'The Thought Emporium' and you can see a video about it here: . In a nutshell the procedure...
  44. nomadreid

    Investigating Unexpected Results in Elementary Experiment

    This concerns an elementary experiment that I (a teacher) have done with several secondary school classes, up until now with success. However, I gave the same instructions to a homeschooling student (in another country , so I couldn’t actually directly oversee the experiment), and the...
  45. haha0p1

    Doing experiment to find the authenticity of Archimedes' law

    I have solved the question like this: Since Volume=Upthrust We need to find the upthrust and the volume V. To find the volume, we will submerge the block in the water and find the difference. To find the upthrust F, we will subtract the weight (finding the weight usinf newton-meter) from the...
  46. PeterDonis

    A Can the double slit experiment distinguish between QM interpretations?

    This paper claims that the double slit experiment can be used to distinguish between QM interpretations: https://arxiv.org/abs/2301.02641 IMO, the paper goes astray right at the start, when it points out that time is a parameter in the Schrodinger equation, not an operator, so that equation...
  47. N

    Particle Maxwell's demon full experiment description

    Hey! Does anyone have the large/full description of Maxwell's demon thought experiment? I've read it on Wikipedia, but I was wondering if someone knows a better source I can reach legally. Thanks.
  48. S

    I Experiment with gamers, random numbers and entanglement

    https://www.wired.com/story/this-random-video-game-powers-quantum-entanglement-experiments/ I don't understand the principle of this experiment. The gamers produced random numbers, and what was done with these numbers then? Was the value like <S> in CHSH inequalities computed, and was it...
  49. N

    Weird barometric formula experiment results in Excel

    Hi, as I know the barometric formula is an exponential equation, but when I did the experiment with a barometer at different heights and inserted these results in Excel for curve fitting, it showed a weird thing, I think. So exponential equation did show that R^2=0.942 and the second-degree...
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