Recall that a cube has eight corners and six square A point charge Q, placed at the center of a cube, produces an electric field strength of E — 130V/m, at each of the eight corners of the cube. What is the strength of the electric field at the centers of the six square faces of the cube?

First we need to determine the distance from the center of the box to each of the corners. Geometrically this distance can be defined as

Distance between center of cube and center of face is,

Then the Electric field will be given for each point as,

The relation between the two electric field then will be

The first electric field in function of the second electric field is

Replacing,

Replacing with the value given,

Therefore the strength of the electric field at the centers of the six square faces of the cube is 390V/m