Q: Which of the following statements best describes the relationship between electric potential energy and the work done by the electric field when moving a charge from point A to point B?

$$\Delta U = -W_{\text{field}}$$

Q: A proton is released from rest near the positive plate of two parallel conducting plates separated by a potential difference of $$450\ \text{V}. $$What is the kinetic energy of the proton when it reaches the negative plate?

$$7.2 \times 10$$^{-17}$$\ \text{J}$$

Question 1

Which of the following statements best describes the relationship between electric potential energy and the work done by the electric field when moving a charge from point A to point B?

Accepted Answer

$$\Delta U = -W_{	ext{field}}$$

Question 2

A proton is released from rest near the positive plate of two parallel conducting plates separated by a potential difference of $$450\ 	ext{V}. $$What is the kinetic energy of the proton when it reaches the negative plate?

Accepted Answer

$$7.2 	imes 10$$^{-17}$$\ 	ext{J}$$

Question 3

Which of the following is true about equipotential surfaces in a conductor at electrostatic equilibrium?

Accepted Answer

The electric field is zero everywhere inside the conductor.

Question 4

The electric potential $$V at a $$distance $$r$$ from a point charge $$q is $$given by which of the following expressions?

Accepted Answer

$$V = \dfrac{1}{4\pi\$$varepsilon_0$$} \dfrac{q}{r}$$

Question 5

A negative charge moves in the direction of a uniform electric field. What happens to its electric potential energy?

Accepted Answer

It increases.

Question 6

Which of the following best describes the relationship between the electric field $$\vec{E}$$ and the electric potential $$V$$?

Accepted Answer

$$\vec{E} = -
abla V$$

Question 7

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

Accepted Answer

$$U = \dfrac{q_1$ q_2$}{4\pi\$$varepsilon_0$$ r}$$

Question 8

Which of the following is NOT true about equipotential lines?

Accepted Answer

They are parallel to electric field lines.

Question 9

A semicircular wire of radius $$R$$ carries a uniform linear charge density $$\lambda. $$What is the electric potential at the center of curvature?

Accepted Answer

$$V = \dfrac{\lambda \pi R}{2\pi\$$varepsilon_0$$ R}$$

Question 10

Suppose the electric potential in a region is given by $$V(x, y, z) = -(5x^2$ + y + z). $$What is the $$x-$$component of the electric field?

Accepted Answer

$$E_x = 10x$$

Question 11

A charged particle moves perpendicular to the electric field lines. What can be said about the work done by the electric field and the change in electric potential?

Accepted Answer

No work is done and the potential remains constant.

Question 12

Which of the following statements about the electron volt (eV) is correct?

Accepted Answer

1 eV is the energy gained by an electron moving through a potential difference of 1 V.

Question 13

A positive charge is moved from a point of higher potential to a point of lower potential. What happens to its electric potential energy?

Accepted Answer

It decreases.

Question 14

Which of the following best describes the electric potential at the surface of a charged conducting sphere of radius $$R$$ and total charge $$q$$?

Accepted Answer

$$V = \dfrac{q}{4\pi\$$varepsilon_0$$ R}$$

Question 15

If the electric field between two parallel plates is $$E$$ and the separation is $$d$$, what is the potential difference between the plates?

Accepted Answer

$$V = Ed$$

Question 16

Which of the following is true for the electric potential energy of a system of three point charges $$q_1$$, $$q_2$$, and $$q_3$$ each separated by a distance $$d$$?

Accepted Answer

$$U = \dfrac{q_1$ q_2$ + q_2$ q_3$ + q_3$ q_1$}{4\pi\$$varepsilon_0$$ d}$$

Question 17

A cancer radiotherapy device accelerates electrons to 10 MeV. What is the energy in joules of one such electron? ($$1\ 	ext{eV} = 1.6 	imes 10$$^{-19}$$\ 	ext{J})$$

Accepted Answer

$$1.6 	imes 10$$^{-12}$$\ 	ext{J}$$

Question 18

Which of the following is a correct statement about the work required to move a charge between two points on an equipotential surface?

Accepted Answer

The work is zero.

Question 19

A system of three point charges $$q_1 = +1.50$$\ \mu	ext{C}$$, q_2$ = +2.50\ \mu	ext{C}$$, $$q_3 = -3.50$$\ \mu	ext{C}$$ are located at (0$$,a)$$, (0$$,0)$$, and (b$$,0)$$, respectively. What is the electric potential at point P$ at (b$$,a)$$?

Accepted Answer

$$V = \dfrac{1}{4\pi\$$varepsilon_0$$} \left( \dfrac{q_1$}{b} + \dfrac{q_2$}{a} + \dfrac{q_3$}{\sqrt{a^2$ + b^2$}} \right)$$

Chapter 23: Electric Potential – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards