176. You have "n" (pair) equal positive point charges, each of magnitude "Q / n", located symmetrically around a circumference of radius "R". I) Show that the electric field E at a point P, located on the line passing through the center of the circumference and is perpendicular to it, at a distance "z" from the center, is that of a charge ring "Q" and radius "R". II) Find the magnitude of the electric field in P, for: Q=4 nC, R=10 cm and z=4 cm. a) 10.5 N/C b) 11.5 N/C c) 12.5 N/C d) 13.5 N/C e) 14.5 N/C

5) A long, thin rod parallel to the y-axis is located at x = -1 cm and carries a uniform positive charge density λ = 1 nC/m. A second long, thin rod parallel to the z-axis is located at x = +1 cm and carries a uniform negative charge density λ = - 1 nC/m. What is the electric field at the origin?

1. Calculate the magnitude of the electric field 2.40 m from a point charge of 5.70 mC (such as found on the terminal of a Van de Graaff).     This is not and will not be graded

1. Two point sources, one with a charge of -3 nC and the other +9 nC, are placed 3m apart as shown below. A third charge is placed at point P, 4 m to the right of the -3nC source. -3nC 3 m 4 m +9 nC *P a) Find the magnitude and direction of the net field at point P. b) Find a location where the net field is zero (if the negative source is at (0,0) what are the coordinates of this point?) Add it to the diagram and label it O. c) Find the approximate field at a test point M that is 1 km (1000 m) to the right of P d) By what factor will the magnitude of the field change if you move M from 1 km to 3 km away? e) Find the magnitude and direction of the force on each of -1pC test charges placed at M, O, and P.