Experimental Definition and 527 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. S

    PhD in Experimental QED: AMO vs Superconductivity?

    Hi all I am looking for a phd in the field of cavity qed - quantum information (experimental). I have read some recent publications in the field from groups working with superconducting qubits and the superconductive approach seems to be more efficient/promising than the optical one. The...
  2. D

    A question about uncertainty using a regression line and experimental data

    Homework Statement I'm new to uncertainty, so I needed a little assistance. The circuit in this experiment was simple, a dry cell connected to a variable resistor. I used an ammeter on the circuit and used a voltmeter across the resistor and took some measurments. The experiment was to...
  3. G

    Understanding Experimental Error

    hi everyone ! when we say (for example)a,b and c are the dimension of Parallelogram a=2.267+- 0.002 cm b=3.376+-0.001 cm and c=0.207+-0.001 cm dose that means that we used equipment to calculat a and another to calculate b and c ? because i know that delta a or b or c is half...
  4. P

    Experimental Particle Physics book(s)

    I' m interested in experimental particle physics (graduate level). All books I know are focused on theory, do you know any book which focus on experiment? tnx
  5. edpell

    Experimental sticky (Hafele-Keating experiment)

    In the experimental sticky it says "They flew atomic clocks on commercial airliners around the world in both directions, and compared the time elapsed on the airborne clocks with the time elapsed on an earthbound clock (USNO). Their eastbound clock lost 59 ns on the USNO clock; their...
  6. S

    Variance of experimental data, compared to Theory

    I'm looking for a way to compare experimental and theoretical data and determining if it obeys a certain law. In particular, I'm writing a computer program that does this and at the moment what I'm doing is, I'm calculating the ratio of each reading with the theoretical result and calculating...
  7. N

    Factors Affecting Acceleration Due to Gravity in Free Fall Experiments

    What factors may cause the experimental value of acceleration due to gravity to be different from tha accepted value in a free fall experiment? Will it be something like air resistance , human error , instruments error or wrong calibration ??
  8. inflector

    Experimental Proof that Neutrons are 3 Quarks?

    I am aware that there is strong evidence for the presence of quarks inside of protons and neutrons through the analysis of deep inelastic scattering experiments. The questions I have specifically relate to the data which supports the composition of the neutron versus the proton, how we have...
  9. S

    What is Experimental Design and How is it Used in Identifying Pure Substances?

    I am doing a Lab report on "Using Properties To Identify Pure Substances" I want to know what does the Experimental design mean. Can anyone tell me what it means? Thanks,
  10. D

    Experimental Values vs. Theoretical Values

    Hi, if say you are determining the speed of sound and you want to compare your values to the theoretical value, would you predict that your experiment values will be higher or lower than the theoretical value and why?
  11. D

    Experimental Values vs. Theoretical Values

    Hi, if say you are determining the speed of sound and you want to compare your values to the theoretical value, would you predict that your experiment values will be higher or lower than the theoretical value and why?
  12. L

    Help me find experimental errors in my bottle rocket experiment, Hurry please?

    Could you please help me find experimental error in bottle rocket experiment that could have affected my results. The experiment is where a bottle gets filled with water, a third of their volume and then they get pressurized to fly in the air. So could you please find me experimental errors...
  13. P

    Programs Experimental Physics post Maths degree?

    Hi everyone, I'm currently doing a joint Pure Maths/Maths Physics degree (I did Experimental Physics in first year of college), but am thinking I may have made the wrong choice. If I go on and finish it, what are my options for getting into Experimental Physics? Would I have to go back and do...
  14. D

    Steam table data vs experimental : Why the difference?

    Hey guys! Was wondering if someone could help me out. I'm doing a thermodynamics topic and have an issue explaining the following : I conducted and experimental procedure involving a boiler apparatus. (Similar to this one >> http://www.armfield.co.uk/th3_datasheet.html" ) Now the idea was to...
  15. L

    Simple Experimental Error Problem

    I have two values: r = 12.3 ± 0.2m d = 0.57 ± 0.03mm I want to divide the two values to find theta (d/r = theta), how do I go about this? I assume that I add the experimental error margins together after the division of 12.3 and 0.57? Giving me: 4.63 x 10^-5 ± 2.0003m
  16. J

    How Can I Apply a Constant Force in an Experimental Design?

    Homework Statement I need a method for my experimental lab procedure that allows me to use the same force multiple times. I need to provide a constant force to object A that causes it to collide with object B -- on a horizontal plane. I thought of using a spring on object A where F=kx but...
  17. R

    Easiest Cavendish G experimental setup

    Can anyone suggest the absolute easiest home-made method to determine grossly the value of G in a Cavendish like experiment?
  18. S

    How Do You Experimentally Measure Quantum Mechanics?

    I am looking for a book or journal articles or anything online with technical details of the apparatus and setups for experimental QM. Something that would answer questions such as: 1. How are singlet states prepared? 2. How do you measure the square of the spin of a particle? Is it a...
  19. K

    Experimental VS theoretical work

    Hi everyone, I am comtemplating the PhD which I would like to embark on late 2010. I am having difficulty deciding whether I should take an experimental or theoretical path. Of course I have been speaking to as many relevant people as I can, and reading lots of information. Just...
  20. E

    Experimental dispersion relation of phonons

    Hi guys, I don't understand how one would exactly determine a dispersion relation of phonons experimentally. There are two equations, one for momentum and one for energy conservation: \vec{k} - \vec{k^{'}} = \vec{G} + \vec{K} \omega - \omega ^{'} = \omega(K) where...
  21. A

    Standard Deviation not equal to experimental uncertainty?

    I am a little confused about the justification behind what we do with things we believe to be poisson distributed. Take for instance, gamma-decay counts from a scintillation detector. Suppose we got 100 counts using a 1 minute integration time. We would then assume that the distribution of...
  22. E

    Emission of Gamma and Beta rays : Experimental Problem

    Hi there! The experiment: I'm counting Gamma and beta rays emitted from gamma and beta cylindrical sources, for counting I'm using a simple GM counter, which has nearly the same cylindrical shape (i mean diameter). As we all know this are electromagnetic emissions, so they distance must...
  23. N

    Experimental Value of Planck's Constant?

    Homework Statement Data obtained in a photoelectric experiment: Wavelength (nm): 140, 117, 93.3, 70.0 Maximum Kinetic Energy of Photoelectrons (eV): 2.76, 4.50, 7.19, 11.61 From the graph, determine an experimental value for Planck's constant (in joules-seconds). Homework Equations...
  24. T

    Optimal Approach for Analyzing Non-Smooth Experimental Data

    Hi, I need your help. From experiments I got data set which I need to analyze. The problem is that my data is not smooth. I tried to fit my data using a polynomial equation, but the fitting was not good enough. I also tried to smooth, spline... but got very different final results. Can anyone...
  25. M

    Aerofoil analysis, CFD and Experimental comparison

    Homework Statement Computational Fluid Dynamics anyone? :D I know someone out there is a genius? I'm trying to understand some of the differences between Experimental results and a Fluent (CFD) analysis of a NACA 0012 aerofoil. There are 3 Cp/x graphs of my results (plotted with negative down...
  26. P

    Programs PhD in Experimental Particle Physics: Oxford, Imperial or Edinburgh?

    Hey, I m obsessed with High Energy Physics and would like to do post-grad in the field. I ve applied to Oxford, Imperial, Edinburgh and Sheffield...and (to my surprise) have been accepted to all four...I m trying to get all the opinion/insights/thoughts possible so if anyone is willing to dish...
  27. T

    Can You Be an Experimental and Theoretical Physicist?

    I would like to build stuff and conduct experiments but i would also like to take walks in the park think of theories. So how do i choose between these two. Maybe i can become an experimental physicist and then come home and write a bunch of stuff. Can you be both an experimental and theoretical...
  28. R

    Experimental Polarization Techniques

    I am currently doing experiments with polarizing optics and reflection from metal surfaces. However it's not as simple as it sounds in textbooks, so I was wondering if anyone had experience in these type of experiments. There seems to be a fundamental problem with identifying the transmission...
  29. E

    Theoretical vs. Experimental Physics

    Which one is more favorable: theoretical physics, or experimental physics? In my opinion, theoretical physics is much better, because it leaves one to ponder the how the world works without having to do the all of the things that an conducting an experiment reuquires.
  30. L

    Webliography: What is the experimental basis of Special Relativity?

    Dear All, The compilation by John Baez about the http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html" is a must read. However, only very few of the references are available online and for free. Also, I have not found any book providing a compilation of such papers...
  31. K

    Photoelectric effect experimental data current vs. intensity vs frequency

    The photoelectric current is known to be directly proportional to the intensity of incident light with fixed frequency. Questions: 1) What are the experimental values of this proportionality constant for various fixed frequencies? 2) Is there a theoretical derivation that provides a formula...
  32. S

    Experimental evidence for Hydrogen Wave Function?

    Hi! I would like to know if there is any direct experimental evidence of the electron distribution inside of the hydrogen atom. In the Wikipedia article http://en.wikipedia.org/wiki/Hydrogen_atom" you can see the solutions of the Schrödinger equation and the graphical representations of the...
  33. S

    Spontaneous fission experimental discrepancy

    Spontaneous fission experimental discrepancy! Hi, I've been studying the book "Nuclear Physics- Principles and Applications" by John Lilley and I've come into a problem with the reason for the discrepency between experiment values for the activation value and the mathmatical one from the SEMF...
  34. F

    Physics What kinda salaries can experimental physicists expect?

    On average... Whether it be defense, condensened matter, etc., how much? If it's too broad, could you guys just list the ones you do know of?
  35. C

    Any experimental evidence of Doppler shift in light?

    Were there any experiments that proved doppler shift of light on a fast moving object - that it has higher frequency if the object is moving towards you and lower if the object is moving away?
  36. A

    What Could Have Caused an Error in Experimental Buckling Load Calculation?

    Hi, I have a problem with the experimental buckling load that I have deduced for a compressive axial load applied to a tube of circular cross section. The buckling load is 2.34% larger than the theoretical buckling load! The beam is connected to supports via knife edges; these are rigid bodies...
  37. B

    Physical law from experimental data

    Consider that high quality experiments furnish data that relate proper time intervals to coordinate time intervals for different values of the relative velocity (life time dilationf moving mesons). An inteligent computer program could find out the best function of the relative speed which...
  38. N

    Exploring the Difference between Calculated & Experimental Acceleration

    Homework Statement So we did a lab this week in my physics class. We had a car on a horizontal table, that was attached to a string with weights (The weights were over the edge of the table.) We then calculated the experimental acceleration and the calculated acceleration. These numbers were...
  39. I

    How do we calculate experimental errors?

    Homework Statement The problem let's us graph and give values for s(m) (distance) t(s) time and delta t (s) velocity. After plotting my second graph (including error bars) I used it to get the slope and the acceleration. But then it asks to determine the experimental error. Is there any...
  40. George Jones

    Minimum Time Interval: Experimental Evidence?

    Craig Hogen, in his paper Indeterminacy of Holographic Quantum Geometry, Phys. Rev D 78, 087501 (2008), has claimed noise seen in output of the GEO600 interferometric gravitational-wave detector is evidence for a fundamental minimum interval time. What is the time-line for the survival of this...
  41. E

    Experimental physics histogram problem

    Homework Statement You have run an experiment and generated a histogram. Suppose you had 853 counts in the bin centered at 1.60, and 2,439 counts in the bin centered at 1.85. If you were to repeat this experiment (by measuring the same source for the same time period, delta t) you know...
  42. D

    Experimental error for the travelling microscope

    Whats the scale reading error for a traveling microscope Hi At school we done an experiment to determine the refractive index of a liquid using real and apparent depth. We used a traveling microscope a glass beaker and a coin. One question we got was what was the scale reading error...
  43. E

    Experimental questions about the law of momentum

    if say I have two carts that is initially at rest, one of the cart has a plunger and the plunger is set so that it's against the other cart. When I release the plunger both carts will travel at a certain velocity. The law of momentum conservation says that the momentum of the initial system...
  44. K

    Experimental Optics: Solving Challenges with Mach-Zhender & Fibers

    Hi, I have two small issues while carrying out my experiments: 1) While using Mach Zhender interferometer setup to cause a phase delay, I would need to find out, by how much the fringes have moved. But all the fringes look very similar before and after causing the phase delay. Because of...
  45. D

    Programs Experimental Physics Undergraduate Degree?

    I love the experimenting side of Physics. I know you can't actually major in Experimental Physics so out of a couple degrees which one is most likely to focus on Experimenting. Engineering Physics, Physics, Applied Physics, Engineering, Materials Science? Also, what part of Physics has a...
  46. G

    What Experimental Evidence Demonstrates Energy Quantization in Atoms?

    Homework Statement What experimental evidence requires that the emission of energy by an atom be quantized? The Attempt at a Solution I can completely confused on what the question is asking. What do they mean by "experimental evidence"? Do I talk about Bohr and how he proposed that to...
  47. wolram

    What Are the Future Challenges and Opportunities in Testing General Relativity?

    arXiv:0809.3730 [ps, pdf, other] Title: Experimental Tests of General Relativity: Recent Progress and Future Directions Authors: Slava G. Turyshev Comments: revtex4, 35 pages, 10 figures Subjects: General Relativity and Quantum Cosmology (gr-qc) Einstein's general theory of relativity...
  48. L

    Analysing Experimental Data (PHOTOS INCLUDED)

    Homework Statement http://img217.imageshack.us/my.php?image=dscf3381gv1.jpg2. The attempt at a solution http://img113.imageshack.us/img113/6683/dscf3380tp0.jpg It's really confusing, and the teacher didn't really go too much indepth on how to work this, so far i plotted the data, i used...
  49. J

    Bad at maths but good at experimental physics ?

    I want to see some results.
  50. C

    Moving from experimental to theoretical

    Hi all, I'm currently a fourth year physics student, working on my honours degree. The school that I'm at has almost no research happening in theoretical physics, but I've always been more interested in theoretical than experimental physics. For my honours project, I'll be working on...
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