What is bells: Definition and 11 Discussions

A bell is a directly struck idiophone percussion instrument. Most bells have the shape of a hollow cup that when struck vibrates in a single strong strike tone, with its sides forming an efficient resonator. The strike may be made by an internal "clapper" or "uvula", an external hammer, or—in small bells—by a small loose sphere enclosed within the body of the bell (jingle bell).
Bells are usually cast from bell metal (a type of bronze) for its resonant properties, but can also be made from other hard materials. This depends on the function. Some small bells such as ornamental bells or cowbells can be made from cast or pressed metal, glass or ceramic, but large bells such as a church, clock and tower bells are normally cast from bell metal.
Bells intended to be heard over a wide area can range from a single bell hung in a turret or bell-gable, to a musical ensemble such as an English ring of bells, a carillon or a Russian zvon which are tuned to a common scale and installed in a bell tower. Many public or institutional buildings house bells, most commonly as clock bells to sound the hours and quarters.
Historically, bells have been associated with religious rites, and are still used to call communities together for religious services. Later, bells were made to commemorate important events or people and have been associated with the concepts of peace and freedom. The study of bells is called campanology.

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  1. 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...
  2. bhobba

    Why Are You So Tired With Bells Palsy

    Hi Guys I normally post over on the QM section but recently came down with Bells Paulsy. I seem to be making a slow recovery and, fingers crossed, it continues. Will start physio Monday week - wanted things to settle a bit before doing that. But my God I am tired. I normally go to a...
  3. morrobay

    Disconnect With Inequality Realism Assumption And Bells' Lambda

    Bell, QM Ideas - Science 177 1972 :" Strictly, however. a hidden variable theory could be non-deterministic; the hidden variable could evolve randomly (possibly even discontinuously) so that their values at one instant do not specify their values at the next instant" From the locality...
  4. morrobay

    Is Conservation of Momentum Overlooked in Bells Inequality Violations

    In the EPR scenario the correlation results are explained with the conservation laws of classical mechanics as applied to spin. The Bell type inequalities are derived on expected spin values. But the violations of these inequalities are then explained with QM: That simultaneous knowledge of...
  5. morrobay

    Bells' Inequality Spin Violations

    When entangled photons are generated from a cascade of a Calciums' 6s level this inequality : n[y+z-] + n[x-y+] ≥ n[x-z-] is derived for what is equivalent to spin in photons. When the detectors at A and B are parallel the perfect anti correlations are due to conservation laws of angular...
  6. S

    Proving Entanglement - Do we need Bells Theorem?

    Question: Do we really need to spend too much time on Bell's theorem/test when there are numerous/easier proofs of quantum entanglement? The numerous/easier proofs are: - Almost all experiments in which two photons are generated via a) SPDC (Delayed Choice Quantum Eraser, Mach–Zehnder...
  7. S

    Do we have any proof of entanglement other than bells inequalities?

    do we have any proof of entanglement other than Bells Inequalities?bell's inequalities says that: - no physical theory of local hidden variables can reproduce all of the predictions of quantum mechanics or in other words - the correlations in/during Quantum Entanglement (QE) are stronger...
  8. C

    Exploring Spin Correlation in Bells Test Experiments

    I have read a decent amount about bells test experiments and some of that recent thread about it. What I don't get is when they talk about rotating the detector an measuring the electrons spin. And let's use pi mesons that decay into an electron and positron. So if I have both of my detectors...
  9. G

    Bells inequality be satisfied with equivalent local QM?

    I've just listened to an online lecture where Susskind explained Bell's inequality () Basically he shows that classically A\cap \overline{B}+B\cap \overline{C}\geq A\cap\overline{C} Then he uses spin measurements with 0°, 45°, 90° to the z-axis for A, B, C to measure spins of an electron...
  10. S

    Franklin's lightning bells. Easy Question.

    Franklin's lightning bells. Easy Question. Please Help! Homework Statement Assume (for this part only) that the metal bell on the left was not grounded but connected to an insulator. Describe the changes as compared to question 4. So the franklin lighting bells experiment has a bell on the...
  11. J

    Oliver Bells contribution to science

    Despite living most of his life in a cage Oliver Bell is a well known celebrated physics lecturer at the high toynton university. He was the first person to release the string theroy but he was laughed at. Having big ears and a lust for vegetables did not help His claim to fame was that he...