A test charge of −4.0μC placed at the origin experiences a force given by
F=0.12i+0.16jN.
(a) Determine the electric field vector E at the origin, expressing your answer in newton per coulomb.
(b) Express the same field in volt per metre and state its magnitude and direction with respect to the positive x-axis.
(c) If the test charge were replaced by a charge of +4.0μC, what force (vector form) would it experience at the origin?
Give vector answers in component form with appropriate units.