Which has the thicker lamp filament, a 60-W incandescent bulb or a 100-W incandescent bulb?
What will be an ideal response?
Answer: The 100-W bulb has less resistance and a thicker lamp filament, for it draws more current. This is consistent with the power relationship: P = IV. More current I for the same voltage V means less resistance. (It is important to note that both watts and volts are printed on a light bulb. A bulb that is labeled "100 W-120V" is 100 W only if there is 120 V across it. If there is only 110 V across it, then the power output is only 84 W!)
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States that observers cannot detect their uniform motion through space through internal tests
Which of these upcoming observations will help test the idea that Mars' atmosphere thinned due to interactions with the solar wind?
A) Astronomers will use spectrographs on the Keck telescope to measure the density of Mars' atmosphere. B) The upcoming MAVEN orbiter will measure present-day gas loss from Mars' atmosphere. C) Geologists will measure the carbon content of Martian rocks that were transported to Earth by asteroid impacts. D) The Curiosity rover will measure the carbon content of rocks on Mars' surface.
The theory of nuclear astrophysics is that all the heavy elements like uranium are formed in the interior of massive stars. These stars eventually explode, releasing these elements into space. If we assume that at the time of the explosion there were
equal amount of U-235 and U-238, how long ago did the star(s) explode that released the elements that formed our Earth? The present U-235/U-238 ratio is 0.007 0 . [The half-lives of U-235 and U-238 are 0.7 × 10^9 yr and 4.47 × 10^9 yr.]
Series/Parallel Circuits: What is the magnitude of the potential difference between points C and D for the circuit shown in the figure? The battery is ideal, and all the numbers are accurate to two significant figures.
A. 6.0 V B. 4.0 V C. 3.0 V D. 2.0 V