When charging two objects by rubbing them together
a. Neither may be a conductor.
b. They must be made of different material.
c. They will sometimes end up with both being positively charged.
d. The heat produced by friction is a necessary part of this process.
b
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Lens-Maker Formula: A double-convex thin glass lens has equal-magnitude radii of curvature. The focal length of this lens is +31.2 cm and the index of refraction of the glass is 1.52. The lens is to be replaced with a plano-convex glass lens of the same focal length and thickness. The radius of curvature of the convex surface of the replacement lens is 13.0 cm. What should be the index of refraction of the glass of the plano-convex lens?
A. 1.42 B. 1.44 C. 1.40 D. 1.38 E. 1.36
This diagram shows the approximate depths to which different wavelengths of light penetrate Earth's atmosphere. Why does it show an airplane?
A) Much of the infrared spectrum can be observed from an airplane that flies above most clouds. B) Airplanes are useful for astronomical observations at all wavelengths of light that do not reach the ground. C) Telescopes on airplanes are better than telescopes on the ground for both visible-light and infrared observations. D) The airplane is just decorative, indicating that astronomers use airplanes to fly to ground-based observatories.
What makes some astronomers think that Uranus was hit by a large body early in its history?
A. It has no moons. B. It goes around the Sun in a direction opposite to the other planets. C. Its composition is so different from those of Neptune, Jupiter, and Saturn. D. Its rotation axis has such a large tilt with respect to its orbit. E. All of these choices are correct.
The energy balance in a thermodynamic process is expressed in the ______________
Fill in the blank(s) with correct word