1.) Three charges of 3uC, -4uC and 5uC are at the points a, b and c, respectively, arranged as follows: from left to right, a and c are 20 m apart from each other while b is 14 m from a and 6m from c.
a. Determine the magnitude and direction of the force acting at point a and at point c.
b. the magnitude and direction of the field intensity acting at the midpoint of a and c.
c. how many lines of foce pass through a circle of 3 mm radius placed at the point in (b).

2.) Calculate the number of field lines through a circle radius 1 mm normal to the electric field at a point midway between two charges, one of +500sC and the other of -200sC placed 50 cm apart in air. What force is exerted upon a +20sC charge placed at the point?

3.) Three charges of -3uC, 4uC, and 5uC are on a straight line at the points a, b, and c, respectively, Arranged as follows: a and c are 25m apart from each other while b is 10m from a and 15m from c.
a. Determine the magnitude and direction of the force acting at a
b. Determine the magnitude and direction of the field intensity acting at the midpoint of a and b
c. the potential at point d, that is 25 m from points a and c
d. the potential at point e that is 12.5 m from points a and c
e. the work done in moving a charge of 7uC from point d to e