An ideal air-filled parallel-plate capacitor has round plates and ...

[bcretired]

An ideal air-filled parallel-plate capacitor has round plates and carries a fixed amount of equal but opposite charge on its plates. All the geometric parameters of the capacitor (plate diameter and plate separation) are now DOUBLED.
 
  If the original energy density between the plates was u0, what is the new energy density? A) 16u0
  B) 4u0
  C) u0
  D) u0/4
  E) u0/16

Question 2

Most meteoroids--rocks moving through outer space--have been moving for billions of years. What, if anything, keeps them moving and why?
 
  A) According to Newton's law of motion, their own acceleration keeps them moving.
  B) According to the law of inertia, nothing is needed to keep them moving.
  C) According to current theories about the creation of the universe, the big bang keeps them moving.
  D) According to Newton's law of gravity, the force of gravity keeps them moving.
  E) According to Newton's law of gravity, nothing is needed to keep them moving.

[lkoler]

Answer to Question 1

E

Answer to Question 2

B