Transmitting power at high voltage, e.g., 400,000 V, reduces the power loss for transmission lines. But such a voltage would destroy electrical devices in household use. How then can such 400,000 V electricity be used in a normal house?
a. The ground prongs on household plugs reduce the voltage to 120 V.
b. Before reaching households, transformers are used to reduce the voltage appropriately.
c. No matter the incoming voltage, a 120-V device only lets 120 V in.
d. The 400,000 V is just theoretical; long distance transmission lines actually use 120 V.
b
You might also like to view...
Although Uranus and Neptune have no liquid metallic hydrogen in their interiors, they do have magnetic fields
a. True b. False Indicate whether the statement is true or false
Astronomers have decided that, rather than being a planet, Pluto is really just a large member of
A) the asteroid belt. B) the Kuiper belt. C) the Oort cloud. D) the moon system around Neptune. E) an extrasolar planetary system.
Imagine that it turns out that dark matter (not dark energy) is made up of an unstable form of matter and that all of it suddenly decays tomorrow into photons or other forms of energy. Based on current understanding, which of the following would begin to occur?
A) Stars would begin to stop having nuclear fusion in their cores. B) Planetary systems would begin to expand and disperse. C) The galaxies in clusters would begin to fly apart. D) The expansion of the universe would begin coming to a halt.
A star has a parallax of .05". Its distance is
A) 20 parsecs. B) 200 parsecs. C) 66 parsecs. D) 5 light-years. E) 660 light-years.