A small object A, electrically charged, creates an electric field. At a point P located 0.250 m directly north of A, the field has a value of 40.0 N/C directed to the south. What is the charge of object A?

Question

A small object A, electrically charged, creates an electric field. At a point P located 0.250 m directly north of A, the field has a value of  40.0 N/C   directed to the south. What is the charge of object A?

drwls · Answer

Object A must have a negative charge if the direction is south, at a location north of the charge. The charge Q is given by E = 40 = -k Q/R^2, where R = 0.25 m Solve for Q k is the Coulomb constant.