Alternative Energy Demystified, 2nd edition

Stan Gibilisco

Explanations for Quiz Answers in Chapter 9

1. In a nuclear fission reaction, the nuclei of heavy elements such as uranium split up into smaller, lighter nuclei. When this happens, energy is liberated in the form of radiation and high-speed subatomic particles. The correct answer is B.

2. The so-called solar wind actually consists of high-speed subatomic particles, mainly protons and electrons. The correct choice is C. Of course, the sun emits ultraviolet radiation and visible light (choices A and D), but these forms of radiation are not considered part of the solar wind. The sun doesn't emit air molecules, at least not in any significant amounts, so choice B is irrelevant. Again, the correct answer is C.

3. Hydrogen fusion reactions "burn" hotter than fission reactions, so choice B is wrong. Fusion reactions certainly do produce dangerous radiation, so choice C is wrong. The correct answer is A. Hydrogen fusion produces only helium and energy, without any of the hazardous byproducts typical of fission reactions.

4. Despite the high-tech nature of nuclear-powered submarines, the actual mechanical drive system comprises an old-fashioned steam turbine. The nuclear reactions provide the heat necessary to boil water into steam which, under pressure, turns the blades of a turbine that's directly connected to the drive system for the propellers. The correct choice is C.

5. The Daedalus spacecraft could theoretically attain speeds up to about 10 percent of the speed of light, or 30,000 kilometers per second. The answer is C.

6. According to Earnshaw's theorem, magnetic levitation cannot occur with a set of fixed magnets. At least some of them must move or rotate (rotation "qualifies" as motion in this case). The correct choice is D.

7. By definition, a ferromagnetic material concentrates magnetic lines of flux, thereby making a magnetic field stronger (locally) than it would be in air or a vacuum. The correct choice is A. Diamagnetic materials (choice B) weaken magnetic fields by dilating the lines of flux, so that's not the right answer here. As for choices C and D, the terms "hypermagnetic" and "quasimagnetic" aren't part of scientific jargon, so they're irrelevant. Again, the answer is A.

8. By definition, a diamagnetic material weakens magnetic fields by dilating the flux lines. The correct choice is B.

9. Perfect diamagnetism, in which a material expels magnetic fields so that no magnetic flux lines can exist at all, is called the Meissner effect. The answer is A.

10. An ion engine derives its thrust by accelerating positive ions (atomic nuclei) rearward. The result, according to the principle of action/reaction, is forward thrust. The most common positive ions in this application are protons (hydrogen nuclei) or "clumps" of two protons and two neutrons (helium nuclei). The correct choice is C.