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Chapter 29 | Introduction to Quantum Physics 1289
29 INTRODUCTION TO QUANTUM PHYSICS
Figure 29.1 A black fly imaged by an electron microscope is as monstrous as any science-fiction creature. (credit: U.S. Department of Agriculture via Wikimedia Commons)
Chapter Outline
29.1. Quantization of Energy
29.2. The Photoelectric Effect
29.3. Photon Energies and the Electromagnetic Spectrum 29.4. Photon Momentum
29.5. The Particle-Wave Duality
29.6. The Wave Nature of Matter
29.7. Probability: The Heisenberg Uncertainty Principle 29.8. The Particle-Wave Duality Reviewed
Connection for AP® Courses
In this chapter, the basic principles of quantum mechanics are introduced. Quantum mechanics is the branch of physics needed to deal with submicroscopic objects. Because these objects are smaller than those, such as computers, books, or cars, that we can observe directly with our senses, and so generally must be observed with the aid of instruments, parts of quantum mechanics seem as foreign and bizarre as the effects of relative motion near the speed of light. Yet through experimental results, quantum mechanics has been shown to be valid. Truth is often stranger than fiction.
Quantum theory was developed initially to explain the behavior of electromagnetic energy in certain situations, such as blackbody radiation or the photoelectric effect, which could not be understood in terms of classical electrodynamics (Essential Knowledge 1.D.2). In the quantum model, light is treated as a packet of energy called a photon, which has both the properties of a wave and a particle (Essential Knowledge 6.F.3). The energy of a photon is directly proportional to its frequency.