Q: A proton (charge $q = +e$) is placed in a uniform electric field of magnitude $E = 2.0 \times 10^4\ \mathrm{N/C}$ directed to the right. What is the magnitude and direction of the force on the proton?

$F = 3.2 \times 10^{-15}\ \mathrm{N}$, to the right

Q: A uniformly charged insulating sphere of radius $R$ and total charge $Q$ has an electric field at a distance $r < R$ from its center given by:

$E = \dfrac{1}{4\pi\epsilon_0} \dfrac{Q}{R^3} r$

Q: Which of the following is true about the net charge on an isolated conductor?

It resides entirely on the outer surface.

Q: A small test charge $q_0$ is placed at a distance $r$ from a point charge $Q$. What is the electric field at that point?

$E = \dfrac{1}{4\pi\epsilon_0} \dfrac{|Q|}{r^2}$

Question 1

A proton (charge $q = +e$) is placed in a uniform electric field of magnitude $E = 2.0 	imes 10^4\ \mathrm{N/C}$ directed to the right. What is the magnitude and direction of the force on the proton?

Accepted Answer

$F = 3.2 	imes 10^{-15}\ \mathrm{N}$, to the right

Question 2

Which of the following statements about electric field lines is correct?

Accepted Answer

Electric field lines begin on positive charges and end on negative charges.

Question 3

A small negative charge is placed near a large, isolated, positively charged conducting sphere. What is the direction of the electric field at a point just outside the surface of the sphere?

Accepted Answer

Radially outward from the center of the sphere

Question 4

A thin, infinite sheet has a uniform surface charge density $\sigma = 5.0 	imes 10^{-6}\ \mathrm{C/m^2}$. What is the magnitude of the electric field produced by the sheet?

Accepted Answer

$E = \dfrac{\sigma}{2\epsilon_0}$

Question 5

Which of the following best describes the electric field inside a uniformly charged conducting sphere?

Accepted Answer

It is zero everywhere inside the sphere.

Question 6

A point charge $q$ is located at the center of a spherical Gaussian surface of radius $r$. What is the net electric flux through the surface?

Accepted Answer

$\Phi_E = \dfrac{q}{\epsilon_0}$

Question 7

A dipole with dipole moment $\vec{p}$ is placed in a uniform electric field $\vec{E}$. Which expression gives the potential energy of the dipole in the field?

Accepted Answer

$U = -\vec{p} \cdot \vec{E}$

Question 8

Two point charges, $q_1 = +2.0 	imes 10^{-6}\ \mathrm{C}$ and $q_2 = -3.0 	imes 10^{-6}\ \mathrm{C}$, are separated by $0.10\ \mathrm{m}$. What is the magnitude of the force between them?

Accepted Answer

$F = 540\ \mathrm{N}$

Question 9

A long, straight wire has a uniform linear charge density $\lambda$. At a distance $r$ from the wire, what is the magnitude of the electric field?

Accepted Answer

$E = \dfrac{\lambda}{2\pi\epsilon_0 r}$

Question 10

A parallel-plate capacitor consists of two large plates, each with area $A$, separated by a small distance $d$. The plates carry equal and opposite charges $\pm Q$. What is the magnitude of the electric field between the plates (neglecting edge effects)?

Accepted Answer

$E = \dfrac{Q}{A\epsilon_0}$

Question 11

A uniformly charged insulating sphere of radius $R$ and total charge $Q$ has an electric field at a distance $r < R$ from its center given by:

Accepted Answer

$E = \dfrac{1}{4\pi\epsilon_0} \dfrac{Q}{R^3} r$

Question 12

A charged particle of mass $m$ and charge $q$ is released from rest in a uniform electric field $\vec{E}$. What is its acceleration?

Accepted Answer

$a = \dfrac{q}{m} E$

Question 13

Which of the following is true about the net charge on an isolated conductor?

Accepted Answer

It resides entirely on the outer surface.

Question 14

A small test charge $q_0$ is placed at a distance $r$ from a point charge $Q$. What is the electric field at that point?

Accepted Answer

$E = \dfrac{1}{4\pi\epsilon_0} \dfrac{|Q|}{r^2}$

Question 15

A closed surface encloses a net charge of $-2.0 	imes 10^{-6}\ \mathrm{C}$. What is the net electric flux through the surface?

Accepted Answer

$\Phi_E = -2.3 	imes 10^5\ \mathrm{N\cdot m^2/C}$

Question 16

A dipole is placed in a uniform electric field. Which of the following statements is correct?

Accepted Answer

The net force on the dipole is zero, but it experiences a torque.

Question 17

A metal sphere is given a net negative charge and is isolated in space. What is the direction of the electric field just outside its surface?

Accepted Answer

Radially inward toward the center

Question 18

A continuous charge distribution has a volume charge density $\rho$. What is the infinitesimal charge $dq$ in a small volume element $dV$?

Accepted Answer

$dq = \rho dV$

Question 19

Which of the following is a correct application of Gauss's Law?

Accepted Answer

The net electric flux through a closed surface depends only on the net charge enclosed.

Electric Charge, Electric Field, and Gauss's Law: Exam 1 Review Notes

Study Guide - Practice Questions

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