At three of the vertices of a rhombus are point charges as shown in the figure. The diagonal length of the rhombus is 3 inches and 4 inches. 

A. Calculate the field strength (size and direction) in the center of the rhombus.

B. Calculate the force that will be applied to a 10-uc charge if placed in the center of the rhombus.

C. Change the sign of the 4uc charger in the lower vertex. What will now be the potential in the center of the rhombus and at the fourth vertex?

D. Calculate the work required to move the uc-10 charge from the fourth vertex to the center of the rhombus. 

E. Is it possible to place a charge in the original circle at the fourth vertex so that the field strength in the center of the rhombus will be reset? If so you need to calculate the charge if not then you need to reason and Is it possible to place a charge in the original circle at the fourth vertex so that the potential in the center of the rhombus is reset? If so calculate the charge if not to reason