What is Test: Definition and 1000 Discussions

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  1. misbah alshaybani

    B Why is the test charge always positive?

    why test charge is always positive ?
  2. L

    B Bell inequality test without polarisation?

    Was trying to understand the inequality test. The only article ever that I've found that explains it simply is the 1981 article, Bringing home the atomic world: Quantum Mysteries For Anybody. All other explanations require trust and understanding of polarisation, which is a huge deal. So i now...
  3. Euge

    POTW A Test for Absolute Convergence of a Series

    Let ##\{a_n\}_{n = 1}^\infty## be a sequence of real numbers such that for some real number ##p > 1##, ##\frac{a_n}{a_{n+1}} = 1 + \frac{p}{n} + b_n## where ##\sum b_n## converges absolutely. Show that ##\sum a_n## also converges absolutely.
  4. Freyja

    Wiesen Mechanical Aptitude Test

    Good day everybody, In a nutshell, I have to take the Wiesen Test for mechanical aptitude before this upcoming 24th, so less than a week from now. I am aware that this might seem a really simple task, and the theoretical concepts are indeed really easy, but the issue would be the timing; I will...
  5. Astronuc

    Jules Horowitz Reactor (JHR) Material Test Reactor

    The JHR Material Test Reactor is currently under construction at the CEA Cadarache centre. https://jhrreactor.com/en/about/ The CEA began exploring the possibility of designing and building a new reactor to replace its material test reactor called Osiris* in the 1980s and 1990s. The JHR...
  6. chwala

    I Understanding the nth-term test for Divergence

    There are several examples that i have looked at which are quite clear and straightforward, e.g ##\sum_{n=0}^\infty 2^n## it follows that ##\lim_{n \rightarrow \infty} {2^n}=∞## thus going with the theorem, the series diverges. Now let's look at the example below; ##\sum_{n=1}^\infty...
  7. chwala

    Understanding the Wilcoxon-signed Rank test

    Reference; https://en.wikipedia.org/wiki/Wilcoxon_signed-rank_test#:~:text=The Wilcoxon signed-rank test,-sample Student's t-test. I have managed to go through the literature (it is pretty straight forward). In general Wilcoxon-rank method applies to data with unequal variances otherwise...
  8. chwala

    Test of hypothesis for independent samples

    Reference; https://www.statisticshowto.com/probability-and-statistics/t-test/ My question is, can we as well have 'subtract each ##x## score from each ##y## score?' thanks. ...t-tests after all are easy to comprehend; as long as one knows the types; i.e 1. indepedent sample tests (compares...
  9. chwala

    Solve the given problem that involves Test of Hypothesis

    Consider the given table below; 109.99 112.46 153.23 111.60 128.47 108.27 94.33 92.98 112.57 76.72 129.59 136.12 My take; We shall use t-distribution as the given sample is less than ##30##. Therefore using ##(n-1)## degree of freedom and ##95\%## confidence level we shall...
  10. P

    Help needed with Varactor diode test circuit

    In the circuit simulator there is no voltage at the Varactor cathodes when Vbias is zero, but depending on the Varactor I use on the breadboard it can be as high as 7.4 volts! There is minimal current through the series resistor when Vbias is applied in LTSPICE, but I always see a significant...
  11. G

    I Few Questions about: TU delft "A loophole-free Bell test"

    Electrons in diamonds are not entangled. Is above statement correct? Spin of emitted fotons if detected separately would not show any correlation? Is above statement correct? Is there assumption that spin of emitted fotons cannot change when reflecting or passing through beam spliter? Or...
  12. robertphy

    Make a test based on online available exercises (looking for websites)

    Hi, a teacher and I have been looking for websites to take Math/Physics exercises from, put them together as a test, print it and pass it to students. I know there are many websites that give you tools to write your own exercises (mainly many LMSes). But we'd like to pick exercises already...
  13. Z

    Divisibility Test: Determine if a Number is Divisible by 6, 8, 4

    Mod note: Moved from technical forum section, so missing the usual sections. Hi am 16yo and i was unable to tackle this quiz even despite trying some online calculators. i hope someone can explain to me step by step. thanks In each of the following numbers without doing actual division...
  14. A

    A Why Statistical Theories of Mental Test Scores?

    In 1968, Lord and Novick published a book called Statistical Theories of Mental Test Scores. I wonder why they used the adjective 'statistical'. Does this suggest that the theories mentioned are not psychological theories and, if so, what could be the meaning of such theories? Should these...
  15. V

    B Videos from Big Event 2015 (Växjö): Loophole free Bell test

    vhttps://play.lnu.se/media/t/0_hgz7034c A.Zeilinger: The Future of Bell Experiments. https://play.lnu.se/media/t/0_6jkhpefo G. Weihs: Violation of Bell’s Inequality under Strict Einstein Locality Conditions https://play.lnu.se/media/t/0_q2r30syq R. Hanson: From the first loophole-free Bell...
  16. H

    Unable to use Cauchy's criterion to prove this Alternating test

    For any fixed ##N##, we have $$ |s_{N+k} - s_N| = | (-1)^{N+2} a_{N+1} + (-1)^{N+3}a_{N+2} + \cdots + (-1)^{N+k+1}a_{N+k} | \lt |a_{N+1}| + |a_{N+2}| + \cdots + |a_{N+k}| $$ Though, from ##\lim (a_n) = 0## we can establish ## n \geq N \implies |a_n| \lt \varepsilon##, that is all the individual...
  17. shivajikobardan

    Comp Sci Poker test: probability of Full House (confusion)

    I'm studying this for poker test. This should not be memorized as this has 3,4 and 5 digit versions. Memorizing all of them isn't possible. So I need a way to calculate them. I'm trying to learn through this example. I'm not getting the process(I know math behind it ie permutations...
  18. shivajikobardan

    MHB Chi-square test vs K-S test of uniformity, is it necessary to normalize values between 0-1?

    Say two digits numbers are given like 10,20,30,55,95,85,12,13,52...etc. Is it necessary to normalize them to numbers between 0 to 1? i.e 0.10 for 10, 0.20 for 20 and so on? I've read this to be the case for K-S test. But I'm not sure for chi-square test. I'm not 100% sure on this information as...
  19. kuruman

    B Rolling Motion Test: Take the Challenge and Justify Your Answers

    I am posting this to generate a parallel discussion to this ongoing thread. It seems that some participants in that thread have doubts and confusion about rolling motion that might be better addressed separately from the homework problem in question. It is a simple test of one's understanding...
  20. cemtu

    Ways to test a switching IC like TOP266EG with a multimeter?

    What are the ways to test a switching IC TOP266EG with a multimeter?(measuring it outside of card circuit)(after uninstalling the component from the card) Link to the datasheet: TOP266EG Datasheet(PDF) - Power Integrations, Inc. (alldatasheet.com) Here is the DATASHEET picture: TOP266EG...
  21. Mayhem

    I Shapiro-Wilks test and the order statistic

    Given the Shapiro-Wilk test value W: where I'm interested in the numerator. If my data is sorted in ascending order, my understanding is that $x_(i) = x_i$. Is that correct?
  22. B


    1. You are working in a company facing attrition problems of the customer service representatives for the past five years. The company president proposed that if the attrition rate is at least 10 per month, then the salary scale, compensation package, and professional development programs for...
  23. B

    MHB Test of hypothesis involving the population mean 𝝁 when the variance is known

    1. The Head of the Mathematics Department announced that the mean score of Grade 11 students in the second periodical test in Statistics was 89, and the standard deviation was 12. One student believed that the mean score was less than this, randomly selected 34 students, computed their mean...
  24. Pipsqueakalchemist

    Studying How do I study for test?

    At this point I just can’t take a test. I split my 3rd year up to have a smaller course load to get higher grades for grad school and got 60s on almost every test. My friends who have double my course load do just as good if not better. I’ve given on grad at this point. For 2nd third year please...
  25. B

    How to test for a purity of a chemical compound

    If you had this chemical compound, for example, how could you test if its pure? $$C_{15}H_{11}I_4NO_4$$
  26. S

    Conditional probability of a test records this positive result

    My attempt: $$P(\text{B is positive}|\text{A is positive})=\frac{P(\text{B is positive} \cap \text{A is positive})}{P(\text{A is positive})}$$ $$=\frac{P(\text{B is positive})\times P(\text{A is positive})}{P(\text{A is positive})}$$ $$=P(\text{B is positive})$$ $$=0.01 \times 0.99 + 0.99 \times...
  27. R

    How much risk with first nuclear explosion test?

    How sure were those involved with the first nuclear explosion test that there wouldn't be an unanticipated reaction of the explosion continuing beyond the material intended? I.e. that the Earth wouldn't go up in a ball of fire, the scientist's last utterance wouldn't be "Oops..."?
  28. nmfowlkes

    Question About a Test Charge Near a Conductor

    I am confused because I thought this was a method of charging a conductor. Why would the system be reaching a state of equilibrium?
  29. J

    How calculate lift/drag using static pressure taps in wind tunnel test?

    An airfoil section in a wind tunnel has many static ports/holes/taps on its upper and lower surface. These static ports can only read static pressure which acts perpendicularly to the local airfoil surface. In place A are static ports that read a pressure value of relative -100 Pa . This...
  30. C

    Prove limit comparison test for Integrals

    Attempt: Note we must have that ## f>0 ## and ## g>0 ## from some place or ## f<0 ## and ## g<0 ## from some place or ## g ,f ## have the same sign in ## [ 1, +\infty) ##. Otherwise, we'd have that there are infinitely many ##x's ## where ##g,f ## differ and sign so we can chose a...
  31. N

    AC Hipot Test on MOSFET: Can It Be Done?

    Hi, I have a test board that I would like to do an AC hipot test on a MOSFET with connections across the drain/source. Since because of the built in diode, current flows during the negative half cycle. Is AC hipot possible for a MOSFET, or is DC required?
  32. mishima

    Identification test for Rochelle Salt?

    Hi, I have a high school student who supposedly synthesized a large quantity of Rochelle salt. I was looking for a conclusive chemical test to verify that it was indeed produced. This isn't because I actually suspect anything weird in the student project, its only for educational purposes...
  33. S

    Using comparison tests and limit comparison test

    The answer sheet states that the series converges by limit comparison test (the second way). In the case of this particular problem, would it be also okay to use the comparison test, as shown above? (The first way) Thank you!
  34. berkeman

    DART mission launches to test asteroid deflection

    Um, why are we spending $330M on a mission to (re-)prove that conservation of momentum works in space? What am I missing? https://www.cnbc.com/2021/11/23/spacex-launching-nasa-dart- spacecraft -to-crash-into-an-asteroid.html SpaceX is launching a NASA spacecraft that will crash into an asteroid
  35. M

    Math (online) test at university level for non-student

    Hi all! During the weekend I exercise with math problems from the Calculus book (LINK - Calculus). Are there any tests which I can take on university level (online or physically)? It would be nice if the tests are recognized/accepted by universities as I consider doing a master-study in the...
  36. SpectraPhy09

    Chemistry Libermann's Nitroso test (of Amines)

    My answer is coming a & c but given ans is a, b & c in my textbook. Plz can someone give mechanism for this reaction? Because my teacher only told that 2° and 1° Amines give the test. So answer should be a & c na but it's wrong :(
  37. D

    How to automate tests on a physical model without real data

    I want to code up a (physical) model of an aircraft or car, and I want to create an automated integrated test to check that the code produces reasonable and realistic results. For example, I want to check that the path taken by the aircraft or car is physical and reasonable. However, I don't...
  38. M

    MHB Multiple choice test : random variable

    Hey! 😊 A multiple choice test consists of 10 questions. For every question there are five possible answers, of which exactly one is correct. A test candidate answers all questions by chance. (a) Give a suitable random variable with value range and probability distribution in order to work on...
  39. R

    I A test for a superluminal neutrino?

    The neutrino has been puzzling since its proposal and its experimental confirmation. There have been experimental anomalies with it for every experiment designed to test it. One fact that might be quite key is that measurements of the mass-square of the neutrino has consistently shown it to...
  40. Twigg

    Why are touchscreens becoming popular in test equipment (scopes, etc)?

    Sorry, this might not be the right place for this question. I've noticed newer model oscilloscopes, spectrum analyzers, AWGs, etc. are being made more and more with touchscreens and fewer buttons. Is there an economic incentive to this, or is it just a marketing gimmick? It bugs me because I've...
  41. plmustard

    B Bell Test Configuration Question

    Qutools makes quantum physics kits for educational purposes. Its quED kit is designed to help students learn about entanglement by performing Bell tests. In the manual section 5.1 it describes "the simplest test to verify entanglement of photon pairs." My question is if the entangled photons...
  42. Ackbach

    MHB Uniformly Most Powerful Test for Weibull Distribution

    $\newcommand{\szdp}[1]{\!\left(#1\right)} \newcommand{\szdb}[1]{\!\left[#1\right]}$ Problem Statement: Let $Y_1,\dots,Y_n$ be a random sample from the probability density function given by $$f(y|\theta)= \begin{cases} \dfrac1\theta\,m\,y^{m-1}\,e^{-y^m/\theta},&y>0\\ 0,&\text{elsewhere}...
  43. Ackbach

    MHB Binomial Distribution: Likelihood Ratio Test for Equality of Several Proportions

    $\newcommand{\szdp}[1]{\!\left(#1\right)} \newcommand{\szdb}[1]{\!\left[#1\right]}$ Problem Statement: A survey of voter sentiment was conducted in four midcity political wards to compare the fraction of voters favoring candidate $A.$ Random samples of $200$ voters were polled in each of the...
  44. Ackbach

    MHB Likelihood Ratio Test for Common Variance from Two Normal Distribution Samples

    $\newcommand{\szdp}[1]{\!\left(#1\right)} \newcommand{\szdb}[1]{\!\left[#1\right]}$ Problem Statement: Let $S_1^2$ and $S_2^2$ denote, respectively, the variances of independent random samples of sizes $n$ and $m$ selected from normal distributions with means $\mu_1$ and $\mu_2$ and common...
  45. freddie_mclair

    Extracting mechanical properties from strain-stress plot (real test)

    Hi everyone, recently I was working out an elasto-plastic model to make some residual stress predictions: see it here. Recently I got some real tensile tests results from a lab, therefore I would like to extract a better stress-strain curve to plug into my elasto-plastic model using the...
  46. jaychay

    MHB Limit Comparision Test: Get Help Now

    Can you please help me Thank you in advance
  47. W

    A Using Statistics to Test for Normality of Pi

    Is there a " reasonable" way to test for the normality of ##\pi## , i .e., that every digit occurs with the same frequency? Someone suggested randomly sampling strings of size 20 and outputting the frequency. Then I guess we could average the frequencies among samples , use a chi-squared test...
  48. jaychay

    MHB Cauchy-Riemann Equations test problem

    I cannot figure it out which choice is correct Please help me Please! Thank you in advance
  49. D

    Applying the root test

    in order to solve a series, the root test is applied and I have this limit ## \lim_{n \rightarrow +\infty} \sqrt[n] {\left| {\frac {i^{\frac { n} {3}}} { \frac {2n} {3} +1}} \right| } ## I don't understand why at the second step the numerator becomes 1, cannot recall why it becomes 1, that is...