An Ideal Air-Filled Parallel-Plate Capacitor with Horizontal Plates Has a Plate

Multiple Choice

An ideal air-filled parallel-plate capacitor with horizontal plates has a plate separation of $5.0 \mathrm {~cm}$ . If the potential difference between the plates is $2000 \mathrm {~V}$ , with the top plate at the higher potential, what are the magnitude and direction of the electric field between the plates?

A) $40000 \mathrm {~N} / \mathrm { C }$ downward
B) $40000 \mathrm {~N} / \mathrm { C }$ upward
C) $100 \mathrm {~N} / \mathrm { C }$ upward
D) $100 \mathrm {~N} / \mathrm { C }$ downward