TAILIEUCHUNG - SAT II Physics (SN) Episode 2 Part 6

Tham khảo tài liệu 'sat ii physics (sn) episode 2 part 6', ngoại ngữ, ngữ pháp tiếng anh phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | electrons. The electromagnetic force pulls the electrons into orbit around the nucleus in just the way that the gravitational force pulls planets into orbit around the sun. The radius of an atom s nucleus is about 110 000 the radius of the atom itself. As a result most of the alpha particles in Rutherford s gold foil experiment passed right through the sheet of gold foil without making contact with anything. A small number however bumped into the nucleus of one of the gold atoms and bounced right back. Quantum Physics As physicists began to probe the mysteries of the atom they came across a number of unexpected results along the lines of Rutherford s gold foil experiment. Increasingly it became clear that things at the atomic level are totally unlike anything we find on the level of everyday objects. Physicists had to develop a whole new set of mechanical equations called quantum mechanics to explain the movement of elementary particles. The physics of this quantum world demands that we upset many basic assumptions that light travels in waves that observation has no effect on experiments etc. but the results from transistor radios to microchips are undeniable. Quantum physics is strange but it works. Electronvolts Before we dive into quantum physics we should define the unit of energy we ll be using in our discussion. Because the amounts of energy involved at the atomic level are so small it s problematic to talk in terms of joules. Instead we use the electronvolt eV where 1 eV is the amount of energy involved in accelerating an electron through a potential difference of one volt. Mathematically The Photoelectric Effect Electromagnetic radiation transmits energy so when visible light ultraviolet light X rays or any other form of electromagnetic radiation shines on a piece of metal the surface of that metal absorbs some of the radiated energy. Some of the electrons in the atoms at the surface of the metal may absorb enough energy to liberate them from their orbits .

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