Rank the six combinations of electric charges on the basis of the electric force acting on q1. Define forces pointing to the right as positive and forces pointing to the left as negative. Rank positive forces as larger than negative forces.

a. q1,q2,q3 = Positive(+)

b. q1 = + q2 = + q3 = -

c. q1 = + q2= - q3= +

d. q1= - q2= + q3= +

e. q1= + q2= - q3= -

f. q1,q2,q3 = Negative (-)

Explanation:

Let's define positive to be right. The net force on q2 is the

vector sum of the forces from q1 and q3.

The force has a magnitude of and points to the left.

Handling the signs correctly is critical. The negative signs

come from the direction of each of the forces (both to the left),

not from the signs of the charge.

2. Both charges 1 and 3 have 1 close

neighbor and 1 far neighbor. Will

they experience forces of the same

magnitude?

No, because both forces acting on charge 1 are in the same

direction, while the two forces acting on charge 3 are in

opposite directions. Thus, 1 > 3.

Both charges 1 and 2 have two forces acting in the same

direction. Will they experience forces of the same magnitude?

No, because one force acting on charge 1 is the same

magnitude as one acing on charge 2, while the second force

acting on charge 1 is smaller – it comes from a charge farther away