Electric Forces and Potential Concepts

How is the electric field characterized in physics?

• As a scalar quantity

• As a vector quantity

• As a tensor quantity

• As a pseudovector quantity

How is the electric potential characterized in physics?

• As a scalar quantity

• As a vector quantity

• As a tensor quantity

• As a pseudovector quantity

Particles A and B each have positive charge +Q and are held fixed at two vertices of an equilateral triangle. Point P is located equidistant from each vertex. If a third charged particle is placed at the bottom-right vertex, what charge must it have for the magnitude of the electric field at Point P to be zero?

• +Q

• +2Q

• -Q

• -2Q

Particles A and B each have positive charge +Q and are held fixed at two vertices of an equilateral triangle. Point P is located equidistant from each vertex. If a third charged particle is placed at the bottom-right vertex, what charge must it have for the electric potential at Point P to be zero?

• +Q

• +2Q

• -Q

• -2Q

Particles A and B each have positive charge +Q. Point P is equidistant from A and B. If a third particle with charge +2Q is placed at the bottom-right vertex, why is the magnitude of the electric field at Point P not zero?

• The electric field is a scalar quantity, so its magnitude cannot be zero.

• The electric field is a vector quantity, and the fields from the three charges do not sum to zero.

• The distance from the third particle to Point P is different from the distances of A and B to P.

• The total charge of the system is positive, preventing the electric field from being zero.

Particles A and B each have positive charge +Q. Point P is equidistant from A and B. If a third particle is placed at the bottom-right vertex, what charge is required for the electric potential at Point P to be zero?

• +Q

• -Q

• +2Q

• -2Q

Particles A and B have positive charges +Q. A third particle with charge +Q is moved from very far away to the bottom-right vertex. How does the work done (W1) to move this particle relate to the initial electric potential energy (U_i1) of the system (particles A and B only)?

• W1 is negative, as the external force opposes the attractive electric force.

• W1 is zero, as the particle is moved from infinity.

• W1 is positive, as the external force opposes the repulsive electric force.

• W1 is equal to U_i1.

Particles A and B have positive charges +Q. A third particle with charge -Q is moved from very far away to the bottom-right vertex. If the initial electric potential energy (U_i2) of particles A and B is represented by 2 units, and the work done (W2) to move the -Q particle is -4 units, what is the final electric potential energy (U_f2) of the system?

• +6 units

• +2 units

• -2 units

• -6 units