Q: Which of the following best describes the relationship between the change in potential energy $$\Delta U$$ and the work done by interaction forces $$W_{\text{interaction}} in a $$system of conservative forces?

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

Q: A proton is released from rest at the surface of a sphere charged to $$+1000\ \text{V}$$ with a radius of $$1.0\ \text{cm}. $$What is the charge $$Q on $$the sphere?

$$Q = 4\pi \$$epsilon_0$$ R V = 0.56\ \text{nC}$$

Question 1

Which of the following best describes the relationship between the change in potential energy $$\Delta U$$ and the work done by interaction forces $$W_{	ext{interaction}} in a $$system of conservative forces?

Accepted Answer

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

Question 2

A proton is released from rest at the surface of a sphere charged to $$+1000\ 	ext{V}$$ with a radius of $$1.0\ 	ext{cm}. $$What is the charge $$Q on $$the sphere?

Accepted Answer

$$Q = 4\pi \$$epsilon_0$$ R V = 0.56\ 	ext{nC}$$

Question 3

In a uniform electric field $$E$$, a positive charge $$q$$ moves a distance $$s in $$the direction of the field. What is the change in electric potential energy $$\Delta U$$?

Accepted Answer

$$\Delta U = -qEs$$

Question 4

Which statement about the electric potential $$V$$ due to a point charge $$q at a $$distance $$r is $$correct?

Accepted Answer

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

Question 5

A water molecule (electric dipole moment $$p = 6.2 	imes 10$$^{-30}$$\ 	ext{Cm}) is $$aligned with a uniform electric field $$E = 1.0 	imes 10^6$\ 	ext{N/C}. $$How much energy is required to rotate the molecule by $$90^\circ$$?

Accepted Answer

$$\Delta U = pE$$

Question 6

A proton with initial speed $$v_i = 2.0 	imes 10^5$\ 	ext{m/s}$$ enters a region with a potential difference $$\Delta V = +100\ 	ext{V}. $$What is its final speed $$v_f$$?

Accepted Answer

$$v_f = \sqrt{v_i^2$ - \frac{2e\Delta V}{m_p}}$$

Question 7

Which of the following is true about the electric field $$E$$ inside a parallel-plate capacitor with voltage $$\Delta V$$ and plate separation $$d$$?

Accepted Answer

$$E = \frac{\Delta V}{d}$$

Question 8

Two point charges $$q_1$$ and $$q_2$$ are separated by a distance $$r. $$What is the electric potential energy $$U of $$the system?

Accepted Answer

$$U = \frac{1}{4\pi \$$epsilon_0$$} \frac{q_1$ q_2$}{r}$$

Question 9

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

Accepted Answer

Kinetic energy decreases, potential energy increases (becomes less negative)

Question 10

What is the electric potential $$V at a $$point on the axis of a uniformly charged ring of radius $$R$$ and total charge $$Q$$, at a distance $$z$$ from the center?

Accepted Answer

$$V = \frac{1}{4\pi \$$epsilon_0$$} \frac{Q}{\sqrt{R^2$ + z^2$}}$$

Question 11

If a positive charge moves toward a region of higher electric potential, what happens to its speed?

Accepted Answer

It slows down

Question 12

Which of the following is true about the zero point of electric potential?

Accepted Answer

It is arbitrary and does not affect the electric field or potential difference

Question 13

Three electrons are placed at the vertices of an equilateral triangle. If the center electron is displaced slightly, what will happen?

Accepted Answer

It will move away from the center due to unstable equilibrium

Question 14

The electric potential at a point due to multiple point charges is:

Accepted Answer

The sum of the potentials due to each charge

Question 15

A dipole in a uniform electric field has potential energy $$U = -pE \cos 	heta. $$What is the minimum potential energy configuration?

Accepted Answer

Dipole aligned with the field ($$	heta = 0^\circ)$$

Question 16

Which of the following is a correct unit for electric field strength $$E$$?

Accepted Answer

$$1\ 	ext{V/m}$$

Question 17

A charged particle moves through a potential difference $$\Delta V. $$What is the change in its kinetic energy?

Accepted Answer

$$\Delta K = -q \Delta V$$

Question 18

Which principle allows the calculation of the electric potential for a continuous charge distribution?

Accepted Answer

Superposition principle

Chapter 25: The Electric Potential – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards