A spring has a spring constant of 200 N/m. How much elastic potential energy is stored in the spring when it is stretched by 0.1 meters? A:2000 J B:20 J C:0 J D:1 J

The electric field between square plates of a parallel-plate capacitor has magnitude e. the potential across the plates is maintained with constant voltage by a battery as they are pulled apart to twice their original separation, which is small compared to the dimensions of the plates. the magnitude of the electric field between the plates is now equal to a)e b)e/4 c)e/2 d)4e e)2e