Answers

The electric field arrow should point UPWARD. The electric field arrow shows you the direction and strength of the force that would be exerted on a positive charge. So draw in a + charge alongside A. The + charge will be pushed upward by the positive charge in the ground and pulled upward by the negative charge in the cloud.

2.

A NEGATIVE charge in the center of the picture would produce this pattern of electric field arrows. The electric field arrows show you the direction and strength of the force that would be exerted on a positive charge. The direction of the force exerted on a negative charge will be opposite the electric field arrow. A negative charge placed somewhere in the pattern will move OUTWARD away from the negative charge in the center of the picture.

3.

A positive charge placed at A will be pushed to the left by the right charge and pushed to the right by the left charge. Since the + charge is midway between the two positive charges the forces will be equal and opposite. The total force will be zero.

A positive charge placed at B will be pushed to the right by the left charge and pulled to the right by the right charge. The net force will point to the right.