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. Dopplershift

    I Understanding the Einstein Train Thought Experiment: Scenario Comparisons

    Hey all, I was re-reading my quantum mechanics books and I noticed that different books have different scenarios for the Einstein Train thought experiment. And I was just wondering if I understood it correctly. Scenario 1: A person inside a moving train flashes a light beam that goes in both...
  2. V

    What Happens to Copper (II) Chloride Solution Under Different Conditions?

    Homework Statement For this experiment we studied the equilibrium system CuCl42+(aq) ↔ Cu2+ + 4Cl-(aq) + heat Net reaction shift is observed by looking at colour changes -CuCl42+(aq) become green (shift to left) - Cu2+ is blue and Cl-(aq) is colourless (shift to right) What occurs when you put...
  3. C

    B Delayed choice experiment and FTL communication

    I've been thinking about a communication system that could allow faster than light communication. The basic principle that would make this system work come from the double-slit experiment and Wheleer's delayed choice experiment, taking advantage of the different patterns that would appear on a...
  4. Davephaelon

    I Double slit experiment with electrons

    When it's desired to detect an electron coming through one of the slits in the mask of the double slit experiment, how exactly is the detection done without blocking the electron from reaching the background screen? In another thread it's mentioned that a semiconductor detector is placed behind...
  5. E

    I A question about the delayed choice quantum eraser experiment

    This delayed choice quantum eraser experiment captured my attention and after deep thought about it, I find it really startling and totally punishing to my common sense. My question is: Can you predict the future, say, a human's mind, using the quantum eraser? I imagine a modified version of the...
  6. T

    Experiment using a Wheatstone Bridge

    Homework Statement Determine the unknown resistance using a Wheatstone Bridge. Homework Equations Unknown Resistance = known resistance (100-Length) / Length The Attempt at a Solution I've connected the set up as shown in the pictures but my only concern is, I don't have a resistance box so...
  7. G

    B Electron diffraction experiment puzzle

    In classical Physics wave theory (GCSE level) we talk about waves diffracting through a gap if the gap is similar size to (or smaller than) the wavelength of the waves. When firing fast electrons at a carbon target (teltron tube A level type apparatus) is it sufficient to say that if the de...
  8. Quotidian

    B A non-physicist's question on the double-slit experiment

    OK this question comes from a late-night discussion, er, argument, about the famous double-slit experiment. One of the interesting facts about the double-slit experiment is that the interference pattern that appears on the screen doesn't seem to be affected by the rate at which electrons are...
  9. A

    Role of accelerating voltage in Davisson Germer experiment

    Hello everyone, We know Davisson & Germer experiment confirms the wave nature of electron(matter). Positions of Constructive Interference produces high intensity. So at different scattering angle intensity should be different. That's fine I understand why scattering angle(position) matters for...
  10. T

    Experiment: Measuring the focal length of a converging lens

    Homework Statement You are required to set up a light source, an object grid, a converging lens and a screen so that a quantitative investigation of object and image distances can be performed. Tabulate corresponding object and image distances (p and p' respectively). Also tabulate values of...
  11. C

    B Why target is putting rotated on DDX experiment?

    Hello. I have a question about DDX (double-differential cross-sections) experiment. On DDX experiment, people are putting the target rotated about 45 degree. I wonder why they put the target rotated and what benefit exist because of that. Thank you
  12. D

    How Do You Calculate the Displacement in Thompson's Cathode Ray Tube Experiment?

    Homework Statement What is the distance Δy between the two points that you observe? Assume that the plates have length d, and use e and m for the charge and the mass of the electrons, respectively. Express your answer in terms of e, m, d, v0, L, and E0. Homework Equations kinematics...
  13. Cocoleia

    Young's double slit experiment with the source being a slit

    Homework Statement Here i am asked to find the phase difference. Homework EquationsThe Attempt at a Solution I know that usually the equation is mλ=asinΘ
  14. S

    B Gravitational lensing thought experiment

    Hello all, I'm starting to learn the math in physics and have the following thought experiment I want to use to work through something I own. The setup: There is a wall 10m from the center of a 1m diameter sphere. There is a 1m diameter light source casting a 1m diameter shadow on the wall...
  15. Bloopy

    B Doubt regarding Rutherford's Alpha Scattering Experiment and Impact Parameter

    It is mentioned in my Textbook that if alpha-particle has large impact parameter, it gets scattered through small angles and vice versa. I understand that impact parameter is defined as the perpendicular distance between the path of a projectile and the center of the nucleus. I am unsure how...
  16. Alanay

    Could Walking Like a Gorilla Increase Strength?

    I was just thinking while watching the Zookeeper movie. If a child is born and we teach it how to move on it's legs and knuckles instead of just it's legs would it end up being a great deal stronger than people it's age? I think the most weight ever lifted by man was 450 KG, and an average...
  17. bubblegumandcameras

    Motion under variable acceleration experiment

    Used a mass attached to a dynamic cart via pulley to examine motion under variable acceleration. As the mass was increased, my calculated friction force shows a decrease. I know that friction should increase with larger mass. Any suggestions as to why my calculations show a decrease? Used the...
  18. K

    Thoughts Experiment about Frame of References

    Homework Statement The Observer (me) is at Inertial Frame of Reference: 1) I am sitting at a car moving east v=30 km/h relative to earth A bird flying east v = 10 km/h relative to earth What is the speed of bird for me? 2) I am sitting at a car moving east v=30 km/h relative to earth A bird...
  19. henry wang

    How do I calculate uncertainties for this experiment?

    Homework Statement I used error propagation equation to calculate errors in x and y for each individual data. Error in y is negligible. My goal is to find the uncertainty in the gradient. 2. Homework Equations The plotted equation is eV=h\frac{c}{2dsin(\theta)} ,where Plank's constant, h, is...
  20. S

    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...
  21. K

    I Measuring Spin in the Stern Gerlach Experiment

    When we are measuring the spin of the electron in the experiment, we choose the spin property as its eigen state for the measurement. The eigen vectors corresponding to these states could be time dependent. Can we still break the problem into solving time independent Schrodinger Equation and...
  22. N

    B What Happens in a Uniform Magnetic Field: The Stern-Gerlach Experiment

    What effect the magnetic field would have produced had it been uniform?
  23. M

    Lab: Plot graph of resistance, R (in Ohms) versus 1/d^2

    Homework Statement We were given five samples of nichrome wire, each with a different diameter but the same length. A micrometer was used to measure the diameters. We then measured and recorded the electrical resistance, R in Ohms of each nichrome sample with a DMM. I will try to summarize all...
  24. S

    What are some good polymerization chemistry experiment ideas

    I'm very interested in researching polymerization chemistry for my school science fair. All the ideas I have are either too expensive or not complex enough.
  25. P

    Air track - Inclined Plane experiment

    Homework Statement I am about to do an experiment where we masure the average speed of a cart released from the top of an inclined plane that has little friction (air track). The speed measurement is done by a photo gate. This is repeated a hundred times. Homework Equations I need to come up...
  26. Especial

    Millikan Oil drop lab experiment - equation for speed of drop

    Millikan Oil drop experiment. For my current lab, we are recreating the milian oil drop experiment to measure the charge of an electron. However, we are using 1-micron diameter latex spheres in place of oil drops. Problem: I am having difficulty deriving an equation for the speed of the drop...
  27. R

    Advice for representing experimental data

    Hi all, I have recently done my first experiment in fluid mechanics, and it was a gravity current experiment using UDVP. I have augmented the data, as to remove noise, and performed the statistical analysis. I have text files which contain the velocities measured by each sensor over the time...
  28. G

    B Density of air experiment, why it yields these answers?

    Hi, If you had a sealed round bottomed flask on some lab scales and you recorded the mass and then you removed all the air with a vacuum pump and then found the mass of the flask again would the difference between the two readings really be an estimate of the mass of the gas in the flask? The...
  29. E

    I Delayed choice experiment clarification (specific setup)

    I know that clarifications about delayed choice experiment was asked million times, and I understand the idea, but I was not able to find the discussion of this particular situation anywhere, though I tried hard. This setup is described in Brian Greene's Fabric of the Cosmos book (note my...
  30. N

    Determine the density at which it sinks -- experiment

    Homework Statement Hello :) This is a last resort. I'm stuck on what to do to complete this lab report table. We are required to conduct an online simulation at this link: Buoyancy Online Simulation This is the document of the lab report I'm required to fill up (I'm stuck at part 2) Homework...
  31. Sanzmatic

    Misc. What kind of projects can I do at home?

    Hello, i am a high school student who is interested in physics. Me and my friends want to build something cool. Can be anything related to science. Nothing too complicated but nothing too easy. Something interesting and safe. No dangerous suggestions please. I do not have any qualifications as i...
  32. Bishamonten

    I Understand Michelson-Morley Experiment from Feynman Lectures

    http://www.feynmanlectures.caltech.edu/I_15.html#Ch15-S3 I'm reading through Feynman's chapter on special relativity in the first volume of his books in order to have a more comprehensive idea of it as I go through the special relativity homework given to us as extra credit for our...
  33. akashpandey

    B Why Does Mercury Enter Water in Andrews' CO2 Experiment?

    Why mercury go inside the water in andrews experiment. Because as we know density of mercury is greater than water so why mercury go inside the water in andrews experiment on co2.
  34. GiuseppeP

    I Double slit experiment: two persons are checking the experiment

    Hello, in the double slit experiment, what will be the result if two persons are checking the experiment using the same equipment to perform the experiment, but one person will take note from which slit is passing the electron while the other is not checking. Will they see the same thing...
  35. J

    B Decoherence thought experiment

    Let's say a memory qubit inside a quantum computer is in state ## α \left|1\right>+β\left|0\right> ## This computer is equipped with a device that emits photons that carry the same qubit as the aforementioned memory location. Alice and Bob, that are very far from each other, receive and...
  36. S

    Pendulum experiment systematic errors

    Homework Statement So we had to the simple pendulum experiment and were measuring the effect of the length of the pendulum on its period of motion. However, our results produced a line of best fit that was significantly higher than the expected line of best fit (with length vs period squared)...
  37. L

    I Does the Michelson-Morley Experiment Solely Confirm Constant Light Speed?

    In Michelson-Morley experiment, the two light beams arrive in phase at the detector, so they say this means waves are traveling at the same speeds because they arrive in phase at the detector, What if the waves started in phase and their path difference is an integer multiple of the wave lengths...
  38. J

    Millikan oil drop experiment charge determination

    Howdy y'all! If you could help with the following question, my physics class and I would be extremely grateful. A charged oil droplet is suspended motionless between two parallel plates (d=0.01m) that are held at a potential difference V. Periodically, the charge on the droplet changes as in...
  39. FallenApple

    Conductor thought experiment: Speed of E field

    I wonder if my thought experiment in proving the finite speed of field lines is valid. Say a spherical conductor has a cavity with positive charge Q inside as shown. say that the beginning of the universe starts at time 0, where there is the charge Q in the cavity and that the conductor is not...
  40. L

    B How Does the Michelson-Morley Experiment Detect Differences in Light Speed?

    In Michaelson-Morley experiment, how woul we know if there was a difference in speeds of reflected beam. Please, I am lost.
  41. T

    Experiment using a potentiometer

    Homework Statement In this experiment, we're trying to study the characteristics of a light bulb. Here are the steps outlined for us: 1. Use a potentiometer to vary the voltage across the bulb measured by the voltmeter V. Collect data of V-values and corresponding I'-values from the ammeter...
  42. O

    Evaluating my experiment; kettle water boiling efficiency

    Homework Statement Evaluate the experiment below, identifying energy loss and errors, and access their effect on the efficiency? The experiment was 'Determining the efficiency of energy conversion of boiling water in an electric kettle'. The method/system - 1. Weigh accurately 1000g of water...
  43. Clara Chung

    B Question about photocell experiment

    Consider a set up with a power supply(dc voltage) ,and a photocell (metal plate + collector) ,and an ammeter. Frequency of light is constant. When V gradually increases from 0 (anode linked to the collector, anode to the metal plate), the photoelectric current is said to be increasing until it...
  44. E

    B Compton’s experiment vs ordinary mirror

    Compton hit the electrons in a carbon target with x-rays and measured the changes in the wavelengths of the scattered photons versus their deflected angle. He correlated that with the energy and momentum the incident photon gave to the electron. My question is why does this not happen in...
  45. MikeW

    Thought Experiment on the Second Law of Thermodynamics

    Hi, I have a thought experiment which seems inconsistent with the 2nd Law of Thermodynamics, so there is probably a flaw in the idea somewhere. Imagine a single molecule of a heavy gas (such as SF6) in a pipe 2.5 metres high and 100mm diametre. The pipe is upright and under the normal...
  46. T

    I Simultaneity: Train and Lightning Thought Experiment

    I am puzzled over einstein's thought experiment on simultaneity. In this experiment, a man is standing on a train platform. A woman is sitted in the middle of a moving train traveling towards the man. When the train is half past the man, lightning strikes at the same instant at both ends of...
  47. F

    Video about pressure in kinetic theory

    Hi, I am looking for a video helping intuition on pressure, in the context of kinetic theory of gases. I remember seeing a video where someone poured a bucketful of little hard balls (lead sinkers for fishing?) onto an electronic scales (a dynamometer, really) showing that this corresponds to...
  48. H

    B Aerogel comet particle capture experiment?

    some years ago it was big news when some aerogel bulk launched at the tail of a comet and bits of the comet dust got stuck in the gel. this was going to be recovered somehow and analysed. I do not know any more about that particular experiment but it died out of the mainstream news. anyone...
  49. TJung

    I A two-fold quantum delayed-choice experiment

    Hello everyone, I am not a physicist but I have been studying this subject. I came across an article and I'm having trouble understanding. I would appreciate if you could help me. https://arxiv.org/pdf/1103.0117v2.pdf Thanks.
  50. S

    I Time travel thought experiment

    Not sure where the best place to post this is, but here it goes. Imagine you were sent back in time, far enough back when a lot of the now known scientific laws, rules equations etc, haven't been discovered yet. You're someone who is intelligible with many scientific fields, and you have...
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