Question 1

Which of the following best describes the relationship between electric potential difference $$\Delta V$$ and the work $$W$$ done by the electric field when moving a charge $$q$$ from point $$a to $$point $$b$$?

Accepted Answer

$$W = -q \Delta V$$

Question 2

A proton is released from rest in a uniform electric field pointing to the right. What happens to its electric potential energy and kinetic energy as it moves?

Accepted Answer

Electric potential energy decreases, kinetic energy increases.

Question 3

Which equation gives the electric potential $$V at a $$distance $$r$$ from a point charge $$q$$?

Accepted Answer

$$V = \dfrac{q}{4 \pi \$$epsilon_0$$ r}$$

Question 4

Which of the following statements about equipotential surfaces is correct?

Accepted Answer

Equipotential surfaces are always perpendicular to the electric field lines.

Question 5

A particle with charge $$q$$ moves from point $$a to $$point $$b in an $$electric field. The potential at $$a is$$ $$V_a$$ and at $$b is$$ $$V_b. $$What is the change in the particle's electric potential energy?

Accepted Answer

$$\Delta U = q(V_b - V_a)$$

Question 6

Which integral expression gives the electric potential $$V at a $$point due to a continuous charge distribution?

Accepted Answer

$$V = \int \dfrac{dq}{4 \pi \$$epsilon_0$$ r}$$

Question 7

The electric field $$E at a $$point is related to the electric potential $$V by $$which of the following expressions?

Accepted Answer

$$E = -\dfrac{dV}{dx}$$

Question 8

A system consists of two point charges, $$q_1$$ and $$q_2$$, separated by a distance $$r. $$What is the electric potential energy $$U of $$the system?

Accepted Answer

$$U = \dfrac{q_1$ q_2$}{4 \pi \$$epsilon_0$$ r}$$

Question 9

Which of the following is true for the potential due to an electric dipole at a point on its axis at distance $$r$$ from the center?

Accepted Answer

$$V = \dfrac{p}{4 \pi \$$epsilon_0$$ r^2$}$$

Question 10

If the electric field in a region is zero, what can be said about the electric potential in that region?

Accepted Answer

The electric potential is constant throughout the region.

Question 11

A charged particle moves along an equipotential surface. What is the work done by the electric field on the particle?

Accepted Answer

The work done is zero.

Question 12

Which of the following best explains why electric potential is a scalar quantity?

Accepted Answer

Because it depends only on the magnitude of the charge and distance, not direction.

Question 13

A thin ring of radius $$R$$ carries a total charge $$Q$$ uniformly distributed. What is the electric potential at the center of the ring?

Accepted Answer

$$V = \dfrac{Q}{4 \pi \$$epsilon_0$$ R}$$

Question 14

Which of the following is the correct expression for the electric potential energy of a system of three point charges $$q_1$$, $$q_2$$, and $$q_3$$ located at distances $$r_{12}$$, $$r_{13}$$, and $$r_{23}$$ from each other?

Accepted Answer

$$U = \dfrac{q_1$ q_2$}{4 \pi \$$epsilon_0$$ r_{12}} + \dfrac{q_1$ q_3$}{4 \pi \$$epsilon_0$$ r_{13}} + \dfrac{q_2$ q_3$}{4 \pi \$$epsilon_0$$ r_{23}}$$

Question 15

A charged isolated conductor has charge $$Q$$ and radius $$R. $$What is the electric potential at its surface?

Accepted Answer

$$V = \dfrac{Q}{4 \pi \$$epsilon_0$$ R}$$

Question 16

Which of the following is a correct statement about the work required to move a charge $$q$$ between two points with potentials $$V_a$$ and $$V_b$$?

Accepted Answer

The work required is $$W = -q(V_b - V_a).$$

Question 17

In a region of space, the electric potential varies as $$V(x) = 5x^2$ (in SI units). What is the x$-component of the electric field at x = 2$ m?

Accepted Answer

$$E_x = -20 V/m$$

Question 18

A lightning bolt transfers a charge of $$5.0 C $$from a cloud to the ground, with a potential difference of $$1.0 	imes 10^8$ V. How much energy is transferred?

Accepted Answer

$$5.0 	imes 10^8$ J$

Question 19

Which of the following is true about the potential at a point due to a group of point charges?

Accepted Answer

It is the algebraic sum of the potentials due to each charge.

Electric Potential: Concepts, Calculations, and Applications

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