Question 1

Imagine that you feed alternating current to an inductor with high inductance and very low resistance. Suppose we slowly increase the frequency of this alternating current while keeping the amplitude $\varepsilon_{0}$ of the applied emf constant. How does the amplitude $i_{0}$ of the alternating current flowing in the coil change (or does it)?
A) 25,000
B) 4000
C) 2500
D) 40
E) 25
F) Some other result (specify).
G) One needs more information to answer.

Accepted Answer

B

Question 2

An iron atom's nucleus has 26 protons and 30 neutrons. A helium atom's nucleus has 2 protons and 2 neutrons. Solid iron is much denser than helium gas. How does the total positive charge in a gram of iron compare to that of a gram of helium?
A) Iron has more positive charge than helium per gram.
B) Iron has the same positive charge as helium per gram.
C) Iron has less positive charge than helium per gram.
D) There is not enough information to tell.

Accepted Answer

C

Question 3

An "up" quark has a charge of $-2 / 3$ times the electron's charge. A "strange" quark has a charge of $+1 / 3$ times the electron's charge. What is the net charge of the quark triplet consisting of two up quarks and a strange quark? (This quark triplet is one of a family of three " $\Sigma$ particles.")
A) $+(5 / 3) e$
B) $+e$
C) $+(1 / 3) e$
D) zero
E) $-(1 / 3) e$
F) -e
G) -(5/3)e

Accepted Answer

The charge of an "up" quark is $+2/3$ times the electron's charge, not $-2/3$ as stated in the question. Therefore, two up quarks have a total charge of $+4/3$ e, and one strange quark has a charge of $-1/3$ e. Adding these together gives a net charge of $+1$ e.

Question 4

An electron a distance $d$ from a proton feels an electrostatic force of magnitude $\left|\vec{F}_{e}\right|$. Imagine that we move the electron so that it is a distance $2 d$ from a helium nucleus (which has two protons and two neutrons). The magnitude of the force on the electron now is $b\left|\vec{F}_{e}\right|$, where $b$ is
A) 4
B) 2
C) 1
D) $\mathbf{1 / 2}$
E) $1 / 4$

Accepted Answer

The force between charged particles is given by Coulomb's law, $F = k \frac{|q_1 q_2|}{r^2}$, where $k$ is Coulomb's constant, $q_1$ and $q_2$ are the charges, and $r$ is the distance between the charges. When the electron is moved to a distance $2d$ from a helium nucleus, the distance $r$ becomes $2d$, and the charge of the helium nucleus ($q_2$) is twice that of a proton due to having two protons. Therefore, the force becomes $F = k \frac{2|q_e q_p|}{(2d)^2}$, which simplifies to $F = \frac{1}{2} k \frac{|q_e q_p|}{d^2}$, or $\frac{1}{2}|\vec{F}_{e}|$. Thus, $b = \frac{1}{2}$.

Question 5

Consider the situation shown below. Assume that the charges are point particles and that point $\mathrm{T}$ is twice as far from the positive particle as it is from the negative particle. At which point might the electric field be zero? (If no labelled point seems exactly right, choose the closest.)

A) A
B) B
C) C
D) D
E) E
F) F
G) T

Accepted Answer

The answer of Consider the situation shown below. Assume that...

Question 6

The electric field vector at a certain point in space points in the direction labelled BB in figure E1.9.
 
-We can consider a set of all chlorine atoms in a block of salt (sodium chloride) to be an "extended object."

Accepted Answer

The answer of The electric field vector at a certain...

Question 7

The electric field vector at a certain point in space points in the direction labelled BB in figure E1.9.
 
-A neutron?
A) A
B) B
C) C
D) D
E) zero
F) Other
G) AA
H) BB
I) $\mathrm{CC}$
J) DD

Accepted Answer

A neutron has a charge of zero.

Question 8

The electric field vector at a certain point in space points in the direction labelled BB in figure E1.9.
 
-A helium nucleus?
A) A
B) B
C) C
D) D
E) zero
F) Other
G) AA
H) BB
I) $\mathrm{CC}$
J) DD

Accepted Answer

The answer of The electric field vector at a certain...

Question 9

What is the direction of the electric field vector $\vec{E}$ at point $P$ in the situation shown below? (Assume that the balls are actually point particles equidistant from $P$.)

A) A
B) B
C) C
D) D
E) zero
F) Other
G) AA
H) BB
I) CC
J) DD

Accepted Answer

The answer of What is the direction of the electric...

Question 10

What is the direction of the electric field vector $\vec{E}$ at point $P$ in the situation shown below? (Assume that the balls are actually point particles, they are equally spaced, and that the negative particles are equidistant from $P$.)

A) A
B) B
C) C
D) D
E) zero
F) Other
G) AA
H) BB
I) $\mathrm{CC}$
J) DD

Accepted Answer

The answer of What is the direction of the electric...

Question 11

What is the direction of the electric field vector $\vec{E}$ at point $P$ in the situation shown below? (Assume that the balls are actually point particles with the same magnitudes of charge.)

A) A
B) B
C) C
D) D
E) zero
F) Other
G) AA
H) BB
I) CC
J) DD

Accepted Answer

The answer of What is the direction of the electric...

Question 12

A point where the electric field created by two charged particles is zero must lie somewhere on the infinite line that goes through those particles.

Accepted Answer

The electric field created by two charged particles can cancel out at a point where the contributions from each particle are equal in magnitude but opposite in direction. This point must lie on the line connecting the two particles, as the electric field vectors are directed along the line connecting the charges for them to cancel out.

Question 13

Imagine that we place a positively charged particle a distance $r$ from a neutral atom, as shown below. Choose your answers for parts $b$ through e from figure E2.12.
-
(a) The electric field of the charged particle causes the initially neutral atom to become charged. T or F?
A) A
B) B
C) C
D) D
E) Zero
F) Other
G) AA
H) BB
I) CC
J) DD

Accepted Answer

The answer of  
Imagine that we place a positively...

Question 14

Imagine that we place a positively charged particle a distance $r$ from a neutral atom, as shown below. Choose your answers for parts $b$ through e from figure E2.12.
-(b) What is the direction of the neutral atom's dipole moment after the charged particle is brought near?
A) A
B) B
C) C
D) D
E) Zero
F) Other
G) AA
H) BB
I) $\mathrm{CC}$
J) DD

Accepted Answer

The answer of  
Imagine that we place a positively...

Question 15

Imagine that we place a positively charged particle a distance $r$ from a neutral atom, as shown below. Choose your answers for parts $b$ through e from figure E2.12.
-(c) What is the direction of the neutral atom's electric field at the location of the charged particle?
A) A
B) B
C) C
D) D
E) Zero
F) Other
G) AA
H) BB
I) CC
J) DD

Accepted Answer

The answer of  
Imagine that we place a positively...

Question 16

Imagine that we place a positively charged particle a distance $r$ from a neutral atom, as shown below. Choose your answers for parts $b$ through e from figure E2.12.
-(d) What is the direction of the force that the interaction between the particle and atom exerts on the particle?
A) A
B) B
C) C
D) D
E) Zero
F) Other
G) AA
H) BB
I) $\mathrm{CC}$
J) DD

Accepted Answer

The answer of  
Imagine that we place a positively...

Question 17

Imagine that we place a positively charged particle a distance $r$ from a neutral atom, as shown below. Choose your answers for parts $b$ through e from figure E2.12.
-(e) What is the direction of the force that the interaction between the particle and atom exerts on the atom?
A) A
B) B
C) C
D) D
E) Zero
F) Other
G) AA
H) BB
I) $\mathbf{C C}$
J) DD

Accepted Answer

The direction of the force on the atom due to the interaction with the particle is determined by Newton's third law, which states that for every action, there is an equal and opposite reaction. If the particle exerts a force on the atom, the atom exerts an equal and opposite force on the particle. The notation $\mathbf{C C}$ likely indicates a specific direction that is opposite to the force exerted by the particle on the atom, thus following the principle of action and reaction.

Question 18

The electric field created by a dipole at an arbitrary point in space around that dipole is always parallel to the dipole's dipole moment vector.

Accepted Answer

The electric field created by a dipole varies in direction depending on the position in space relative to the dipole. It is only along the dipole moment vector at points along the axis extending through the dipole.

Question 19

The dipole moment of an electrically polarized atom always points in the same direction as the external field that has polarized it.

Accepted Answer

The dipole moment of an atom aligns with the external electric field, as the field induces a separation of charges within the atom, causing the dipole to point in the direction of the field.

Question 20

Imagine that we place a dipole a distance $r$ from a neutral atom, as shown below.
 
-(a) Will the dipole polarize the neutral atom? Choose E if not or specify the direction of the neutral atom's induced dipole moment from figure E2.12 if nonzero.
A) A
B) B
C) C
D) D
E) Zero
F) Other
G) AA
H) BB
I) $\mathrm{CC}$
J) DD

Accepted Answer

The answer of Imagine that we place a dipole a...

Quiz 4: Electricity and Magnetism Are Unified

An iron atom's nucleus has 26 protons and 30 neutrons. A helium atom's nucleus has 2 protons and 2 neutrons. Solid iron is much denser than helium gas. How does the total positive charge in a gram of iron compare to that of a gram of helium?

The electric field vector at a certain point in space points in the direction labelled BB in figure E1.9. -We can consider a set of all chlorine atoms in a block of salt (sodium chloride) to be an "extended object."

The electric field vector at a certain point in space points in the direction labelled BB in figure E1.9. -A neutron?

The electric field vector at a certain point in space points in the direction labelled BB in figure E1.9. -A helium nucleus?

What is the direction of the electric field vector E⃗\vec{E}E at point PPP in the situation shown below? (Assume that the balls are actually point particles equidistant from PPP .)

What is the direction of the electric field vector E⃗\vec{E}E at point PPP in the situation shown below? (Assume that the balls are actually point particles, they are equally spaced, and that the negative particles are equidistant from PPP .)

What is the direction of the electric field vector E⃗\vec{E}E at point PPP in the situation shown below? (Assume that the balls are actually point particles with the same magnitudes of charge.)

A point where the electric field created by two charged particles is zero must lie somewhere on the infinite line that goes through those particles.

Imagine that we place a positively charged particle a distance rrr from a neutral atom, as shown below. Choose your answers for parts bbb through e from figure E2.12. - (a) The electric field of the charged particle causes the initially neutral atom to become charged. T or F?

Imagine that we place a positively charged particle a distance rrr from a neutral atom, as shown below. Choose your answers for parts bbb through e from figure E2.12. -(b) What is the direction of the neutral atom's dipole moment after the charged particle is brought near?

Imagine that we place a positively charged particle a distance rrr from a neutral atom, as shown below. Choose your answers for parts bbb through e from figure E2.12. -(c) What is the direction of the neutral atom's electric field at the location of the charged particle?

Imagine that we place a positively charged particle a distance rrr from a neutral atom, as shown below. Choose your answers for parts bbb through e from figure E2.12. -(d) What is the direction of the force that the interaction between the particle and atom exerts on the particle?

Imagine that we place a positively charged particle a distance rrr from a neutral atom, as shown below. Choose your answers for parts bbb through e from figure E2.12. -(e) What is the direction of the force that the interaction between the particle and atom exerts on the atom?

The electric field created by a dipole at an arbitrary point in space around that dipole is always parallel to the dipole's dipole moment vector.

The dipole moment of an electrically polarized atom always points in the same direction as the external field that has polarized it.

Imagine that we place a dipole a distance rrr from a neutral atom, as shown below. -(a) Will the dipole polarize the neutral atom? Choose E if not or specify the direction of the neutral atom's induced dipole moment from figure E2.12 if nonzero.

Imagine that we place a positively charged particle a distance $r$ from a neutral atom, as shown below. Choose your answers for parts $b$ through e from figure E2.12. - (a) The electric field of the charged particle causes the initially neutral atom to become charged. T or F?

Imagine that we place a positively charged particle a distance $r$ from a neutral atom, as shown below. Choose your answers for parts $b$ through e from figure E2.12. -(c) What is the direction of the neutral atom's electric field at the location of the charged particle?