Two point charges, q1= +4uC and q2=+5uC are fixed in position on the x-axis with q1 at the origin and q2=10cm.
a. Setting the potential energy to zero at infinity, calculate the electric potential energy of charge 2.
b. Determine the electric field (both magnitude and direction) at the midpoint between two charges (i.e at position x=5 on the x-axis)
c. After a third charge, q3 is added and fixed on the x-axis at x=15 cm, it is observed that the net force on q3 is 0. Find the value of q3.