Current flows from negative to positive, so based on how your power source is set up, you can determine which way the current is flowing. Flowing current, which is the flow of electrons, has the ability to create its own magnetic field. This means that the rotation of the wheel is certainly not due to transferred momentum from the electron beam, and the results of the experiment should not be taught to students as proof that electrons are particles with mass that carry momentum. The cathode ray tube carries current in the electron beam when the power source is activated. Our measurements yield a maximum impulsive force due to the electrons = (1.1 ± 0.3) × 10N], which is within a factor of two of Thomson's estimate, and which is more than two orders of magnitude smaller than the force that is responsible for the observed acceleration of the paddle wheel = (6 ± 2) × 10N]. ![]() We could then compare the force, which really acts on the wheel to produce the observed motion to the maximum impulsive force that is supplied by the electrons. cathode ray, stream of electrons leaving the negative electrode (cathode) in a discharge tube containing a gas at low pressure, or electrons emitted by a heated filament in certain electron tubes. We then measured the actual acceleration of the wheel in the CRT by video analysis of its motion and determined the moment of inertia of the wheel along with its mass and dimensions. The misconception was not laid to rest, however, and despite an effort in 1961 to draw attention to Thomson's original work and so remove the error from textbooks, the notion that a Crookes paddle wheel CRT demonstrates that electrons carry momentum continues to be taught in high school physics courses and wheel. In 1903 Thomson discounted Crookes' interpretation by calculating that the rate of momentum transfer (which he estimated at no more than 2×10 dyn, equivalent to 2×10 N) would be far too small to account for the observed motion of the wheel, instead attributing the motion to the radiometric effect. The electron current, I in an X-ray tube in operation is given by I ne, where n is the number of electrons per second and e is the electronic charge. ![]() Crookes attributed the motion of the wheel to momentum transfer from the cathode rays (electrons) to the wheel, and interpreted the experiment as providing evidence that cathode rays were particles. ![]() 1) when connected to a high-voltage induction coil. In 1879, in the midst of the debate between English and continental scientists about the nature of cathode rays, William Crookes conducted an experiment in which a small mill or "paddle wheel" was pushed along tracks inside a cathode ray tube (CRT) (similar to that shown in Fig.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |