Four charges of magnitude +q are placed at the corners of a square whose sides have a length d. what is the magnitude of the total force exerted by the four charges on a charge q located a distance b along a line perpendicular to the plane of the square and equidistant from the four charges?

The magnitude of the magnetic field at a certain distance from a long, straight conductor is represented by b. what is the magnitude of the magnetic field at twice the distance from the conductor? a. at twice the distance, the magnitude of the field is 4b.b. at twice the distance, the magnitude of the field is 2b.c. at twice the distance, the magnitude of the field is b/2.d. at twice the distance, the magnitude of the field is b/4.e. at twice the distance, the magnitude of the field remains equal to b.