Two charges q and Q are fixed in place along the x axis. Q = +3.8 nC is at x = -2.0 cm and unknown charge q is located at x = 2.0 cm.

a) It is found that the net electric field is zero at x = -0.76 cm. What is the magnitude and sign of charge q?

b)Sketch both the equipotential lines and the electric field for the system (you need to have at least 5 field lines for the smallest charge and 6 potential lines for each charge)

c)A proton is fired at infinity towards q along the line of the two charges with speed 7.4x10⁴ m/s. How close the proton from charge q before it turns around?