Child with ADHD vs. Ready to ask a question on Biology Forums? Try it out. As Pete is telling Brian a story, Brian frequently interjects with mm-hmm to let Pete know that he How would he write the word form of this amount on a Join Our Community Biology Forums - Study Force is the leading provider of online homework help for college and high school students. Get homework help and answers to your toughest questions in biology, chemistry, physics, math, calculus, engineering, accounting, English, writing help, business, humanities, and more.
Master your assignments with step-by-step solutions to countless homework questions asked and answered by our members. You can ask any homework question and get expert homework help in as little as two hours. Our extensive online study community is made up of college and high school students, teachers, professors, parents and subject enthusiasts who contribute to our vast collection of study resources: textbook solutions, study guides, practice tests, practice problems, lecture notes, equation sheets and more.
With our help, your homework will never be the same! Join for free today. How is Biology Forums - Study Force different than tutoring? New Topic.
Gurjeet Gurjeet wrote Posts: Rep: 0 0. Physics , Which experimental observation led scientists to speculate that cathode rays contained particles that were constituents of all matter? Answers: 1. Answer from: tae The rays were independent of the type of gas in the vacuum tube. Answer from: pedropaulofpedrosapp. B C Explanation: A J. So, the correct option is b. B The figure of the problem is missing: find it in attachment.
Here, we want to find the difference between the two quantities When the electron is in the region with electric field, its motion is accelerated upward. This time can be found from the horizontal motion, which is uniform: So, we get: After exiting the region with electric field, the electron continues its motion with constant velocity. Solving for B0, we find:. Answer from: krystinayagel For the second part I can center one point but the other is off center Therefore the third statement is correct.
Answer from: DnakMeme6e All options are correct Explanation: Thompson's cathode ray experiment lead to the postulation of the Thompson model of an atom, where negatively charged particles electrons were embedded in a positively charged cloud of protons.
Answer from: ehaynie. As you can conclude a. Answer from: vaehcollier. Particles of the cathode rays are fundamental to all matter. Matter contains negative charge and by inference positive charge. There are subatomic size particles in an atom. Cathode rays have mass. The Paschen series and all the rest are entirely IR.
Electron transitions and their resulting wavelengths for hydrogen. While the formula in the wavelengths equation was just a recipe designed to fit data and was not based on physical principles, it did imply a deeper meaning. Bohr was the first to comprehend the deeper meaning. Again, we see the interplay between experiment and theory in physics.
Experimentally, the spectra were well established, an equation was found to fit the experimental data, but the theoretical foundation was missing. The wave-like properties of matter were subsequently confirmed by observations of electron interference when scattered from crystals. Electrons can exist only in locations where they interfere constructively. How does this affect electrons in atomic orbits?
When an electron is bound to an atom, its wavelength must fit into a small space, something like a standing wave on a string. Waves on a String : a Waves on a string have a wavelength related to the length of the string, allowing them to interfere constructively.
Allowed orbits are those in which an electron constructively interferes with itself. Not all orbits produce constructive interference and thus only certain orbits are allowed i. As previously stated, Bohr was forced to hypothesize this rule for allowed orbits. We now realize this as the condition for constructive interference of an electron in a circular orbit. Accordingly, a new kind of mechanics, quantum mechanics, was proposed in The new theory was proposed by Werner Heisenberg.
This described electrons that were constrained to move about the nucleus of a hydrogen-like atom by being trapped by the potential of the positive nuclear charge. By the early 20th century, research into the interaction of X-rays with matter was well underway.
Although classical electromagnetism predicted that the wavelength of scattered rays should be equal to the initial wavelength, multiple experiments had found that the wavelength of the scattered rays was longer corresponding to lower energy than the initial wavelength. In his paper, Compton derived the mathematical relationship between the shift in wavelength and the scattering angle of the X-rays by assuming that each scattered X-ray photon interacted with only one electron.
His paper concludes by reporting on experiments which verified his derived relation:. Because the mass-energy and momentum of a system must both be conserved, it is not generally possible for the electron simply to move in the direction of the incident photon. The interaction between electrons and high energy photons comparable to the rest energy of the electron, keV results in the electron being given part of the energy making it recoil , and a photon containing the remaining energy being emitted in a different direction from the original, so that the overall momentum of the system is conserved.
If the scattered photon still has enough energy left, the Compton scattering process may be repeated. In this scenario, the electron is treated as free or loosely bound. Photons with an energy of this order of magnitude are in the x-ray range of the electromagnetic radiation spectrum. Therefore, you can say that Compton effects with electrons occur with x-ray photons.
If the photon is of lower energy, but still has sufficient energy in general a few eV to a few keV, corresponding to visible light through soft X-rays , it can eject an electron from its host atom entirely a process known as the photoelectric effect , instead of undergoing Compton scattering. Higher energy photons 1.
In a previous Atom on X-rays, we have seen that there are two processes by which x-rays are produced in the anode of an x-ray tube. In one process, the deceleration of electrons produces x-rays, and these x-rays are called Bremsstrahlung , or braking radiation. The second process is atomic in nature and produces characteristic x-rays, so called because they are characteristic of the anode material.
The x-ray spectrum in is typical of what is produced by an x-ray tube, showing a broad curve of Bremsstrahlung radiation with characteristic x-ray peaks on it. The smooth part of the spectrum is bremsstrahlung radiation, while the peaks are characteristic of the anode material. A different anode material would have characteristic x-ray peaks at different frequencies.
Since x-ray photons are very energetic, they have relatively short wavelengths. For example, the Thus, typical x-ray photons act like rays when they encounter macroscopic objects, like teeth, and produce sharp shadows. However, since atoms and atomic structures have a typical size on the order of 0. The process is called x-ray diffraction because it involves the diffraction and interference of x-rays to produce patterns that can be analyzed for information about the structures that scattered the x-rays.
When x-ray are incident on an atom, they make the electronic cloud move as an electromagnetic wave. The movement of these charges re-radiate waves with the same frequency. This is called Rayleigh Scattering, which you should remember from a previous atom.
A similar thing happens when neutron waves from the nuclei scatter from interaction with an unpaired electron. These re-emitted wave fields interfere with each other either constructively or destructively, and produce a diffraction pattern that is captured by a sensor or film.
This is called the Braggs diffraction, and is the basis for x-ray diffraction. Perhaps the most famous example of x-ray diffraction is the discovery of the double-helix structure of DNA in Using x-ray diffraction data, researchers were able to discern the structure of DNA shows a diffraction pattern produced by the scattering of x-rays from a crystal of protein.
This process is known as x-ray crystallography because of the information it can yield about crystal structure. Not only do x-rays confirm the size and shape of atoms, they also give information on the atomic arrangements in materials.
For example, current research in high-temperature superconductors involves complex materials whose lattice arrangements are crucial to obtaining a superconducting material.
These can be studied using x-ray crystallography. X-Ray Diffraction : X-ray diffraction from the crystal of a protein, hen egg lysozyme, produced this interference pattern.
Analysis of the pattern yields information about the structure of the protein. The Compton Effect is the phenomenon of the decrease in energy of photon when scattered by a free charged particle. Compton scattering is an inelastic scattering of a photon by a free charged particle usually an electron. It results in a decrease in energy increase in wavelength of the photon which may be an X-ray or gamma ray photon , called the Compton Effect. Part of the energy of the photon is transferred to the scattering electron.
Inverse Compton scattering also exists, and happens when a charged particle transfers part of its energy to a photon. Scattering in the Compton Effect : The Compton Effect is the name given to the scattering of a photon by an electron.
Energy and momentum are conserved, resulting in a reduction of both for the scattered photon. Studying this effect, Compton verified that photons have momentum. Compton scattering is an example of inelastic scattering because the wavelength of the scattered light is different from the incident radiation. Still, the origin of the effect can be considered as an elastic collision between a photon and an electron.
One of the first to look at their charges more closely was J. Scientists had to use pigs blood because it contained what they needed to make Photofrin. Photofrin is a drug to help cancer patients. Pangaea was the ancient Super continent that once contained all of today's smaller continent. Scientists inferred that nuetral atoms contained postitive charges, because electrons contained negative charges. Mass is always conserved. It is not clear what the experimental setup is, but if a beaker contained a liquid, it is very likely that some of that mass evaporated - went into the atmosphere.
Anyone can eat sperm, if they wish too. Semen, and the sperm contained within it, are perfectly harmless. The main constituents of semen are water, proteins and sugars. Because they contain the raw elements that the planets contained when they were first formed. They are "leftovers" if you will. Logically, for self contained underwater breathing. Zoologists are scientists too! SCUBA tanks are also used to charge certain air guns and cannons for ballistics testing and such.
The Cell volume is increased, for one thing. Surely and Certainly Osmotic forces will move [relocate] cell-matter constituents to adjust to the change; what change - the change in the concentrations of the contents that resulted from the increased quantity of [contained] water.
Embryology is the study of embryos, which are the beginning stages of life. Embryos, often contained in eggs or in the uterus of an animal, provide scientists studying them many clues about development. Marie Curie observed that some minerals that contained uranium gave off more radioactivity than pure uranium.
Believing that these minerals contained small amounts of other, highly radioactive elements, she began to experiment. Eventually, she discovered the elements which she named radium and polonium. Convection in the mantle is thought to be one of the potential driving mechanisms of plate movement.
0コメント