What is gravitational lensing?
A. the temporary disappearance of a star as an object passes in front of it
B. the use of Earth's gravity to shape lenses during grinding
C. the focusing and brightening of starlight by the gravitational field of a foreground object
D. the use of small telescopes to enhance the brightness of stars
Answer: C
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In general, Globular clusters are ________ and ________ than open clusters
Fill in the blank(s) with correct word
A new polymer is developed, and to characterize the electrical properties of the polymer, the capacitance is determined to be 20.36×10-13 F in a parallel-plate capacitor that has square plates with a side length of 10-2 m, and the thickness of the polymer sheet and the spacing between the plates is 10-3 m.
(a) What is the dielectric constant or relative permittivity of this new material? (b) If the capacitance measurement is made with an applied voltage of 10 volts, what is the magnitude of the polarization in the new polymer?
Alone of all the Galilean moons, Callisto shows no sign of plate tectonics
Indicate whether the statement is true or false
A circus diver drops from a high pole into water far below. When he is halfway down
A) his potential energy is halved. B) he has gained an amount of kinetic energy equal to half his initial potential energy. C) his kinetic energy and potential energy are equal. D) all of the above E) none of the above