When a transparency sheet is rubbed with a tissue and the transparency and tissue are then held at rest a short distance apart,
A) the transparency and the tissue exert magnetic forces on each other, because the electron orbits in the two objects are all put into the same alignment.
B) the two objects exert electric forces on each other, because electrons are rubbed off of one and onto the other.
C) the two objects exert magnetic forces on each other, because electrons are rubbed off of one and onto the other.
D) a spark will jump between them, because the rubbing causes electrons to jump from one object to the other.
E) the two objects exert electric forces on each other, because the electron orbits in the two objects are all put into the same alignment.
B
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The Miller indices of a plane are the ______________of the intercepts of the plane along the unit cell axes.
Fill in the blank(s) with the appropriate word(s).
Why does Saturn radiate even more excess heat than Jupiter?
A) Helium rain falling inward generates heat as it descends. B) Saturn's atmosphere contains much methane, which is very flammable. C) Only Saturn is still radiating heat left over from its formation. D) Saturn's thick clouds give it a stronger greenhouse effect. E) Saturn is more massive than Jupiter, so its gravitational compression is stronger.
There is no current in the circuit shown in the figure below until the switch is closed. The current through the 20-? resistor the instant after the switch is closed is either [1] 15 A or [2] 5.0 A, and the current through the 20-? resistor after the switch has been closed a long time is either [3] 5.0 A or [4] 15 A. Which combination of the above choices is correct?
a.
[1] and [3]
b.
[1] and [4]
c.
[2] and [3]
d.
[2] and [4]
e.
None of these
Which one of the choices below represents the preferred practice regarding significant figures when multiplying the following: 10.5 × 8.9 × 3.11?
a. 290.6295 c. 291 b. 290.63 d. 290