C2.4d: The Electromagnetic Spectrum: How light travels The spectrum is the arrangement of all the various forms of electromagnetic radiation in order of decreasing wavelengths or increasing frequencies. Examples of using electromagnetic radiation include listening to the radio, using a microwave oven, a remote control, or a cell phone. The bright lights of a neon sign, getting an x-ray, or even a rainbow are also examples of electromagnetic radiation. All of these are different examples of light energy known as electromagnetic radiation that travels as waves through space. Visible light at wavelengths from 700 to 400 nm is the only form of light our eyes can detect. The longer The wavelength is the distance from one peak to another and the frequency is the wavelength, the lower the energy is. the number of waves that pass a certain point in 1 second. C1.2i: The Wave-Mechanical Model String Theory: Quantum Mechanics In the 1920’s it was becoming apparent that there were some difficulties with the Bohr model of the atom. One difficulty was that Bohr used classical physics to calculate the orbits of the hydrogen atom but this could not be used to explain the ability of electrons to stay in only certain energy levels without the loss of energy. The Bohr model could also not be used to explain that the only change of energy occurred when an electron from one energy level to “jumped” another and could not exist in the atom at any energy level between these levels. In short classical physics could be use to explain how a baseball travels in three dimensional space but it could not be used to explain how an electron travels in three dimensional space, at the subatomic level; the level of the atom. A new approach to the laws governing the behavior of electrons inside the atom was needed and such an approach was developed in the 1920’s by the combined work of many scientists. Their work dealt with a more mathematical model usually referred to as quantum mechanics or wave mechanics. C1.2i, C4.8h, C4.8i: Quantum Mechanics: Electrons Particles or
C2.4d: The Electromagnetic Spectrum: How light travels The spectrum is the arrangement of all the various forms of electromagnetic radiation in order of decreasing wavelengths or increasing frequencies. Examples of using electromagnetic radiation include listening to the radio, using a microwave oven, a remote control, or a cell phone. The bright lights of a neon sign, getting an x-ray, or even a rainbow are also examples of electromagnetic radiation. All of these are different examples of light energy known as electromagnetic radiation that travels as waves through space. Visible light at wavelengths from 700 to 400 nm is the only form of light our eyes can detect. The longer the wavelength, the lower the energy is. The wavelength is the distance from one peak to another and the frequency is the number of waves that pass a certain point in 1 second. C1.2i: The Wave-Mechanical Model String Theory: Quantum Mechanics In the 1920’s it was becoming apparent that there were some difficulties with the Bohr model of the atom. One difficulty was that Bohr used classical physics to calculate the orbits of the hydrogen atom but this could not be used to explain the ability of electrons to stay in only certain energy levels without the loss of energy. The Bohr model could also not be used to explain that the only change of energy occurred when an electron “jumped” from one energy level to another and could not exist in the atom at any energy level between these levels. In short classical physics could be use to explain how a baseball travels in three dimensional space but it could not be used to explain how an electron travels in three dimensional space, at the subatomic level; the level of the atom. A new approach to the laws governing the behavior of electrons inside the atom was needed and such an approach was developed in the 1920’s by the combined work of many scientists. Their work dealt with a more mathematical model usually referred to as quantum mechanics or wave mechanics. C1.2i, C4.8h, C4.8i: Quantum Mechanics: Electrons Particles or
unit_3_electromagnetic_packet.docx