This exam consists of 29 questions; true-false questions are worth 2
points each, three-choice multiple choice questions are worth 3 points
each, five-choice multiple choice questions are worth 6 points each.
The maximum possible score is 102. When the exam was given, the mean
was 66.1; the median was 67. Click here to see the
formula sheet that came with the exam.

A positive point charge Q is located at the origin. A thin,
circular, conducting disk is placed at x = 3 m, with its circular faces
perpendicular to and centered about the x-axis as shown below. The
conducting disk is grounded.

(a)

(b)

(c)

### QUESTION 4*

*This and the next four questions pertain to the following
situation.*
Two charges are placed at (-3, 0) and (0, 0) as shown. The grid
spacing is in meters.

What is the magnitude of the electric force on the 3 mC charge due to the -2 mC
charge?

(a) 1.80 × 10^{-2} N

(b) 5.99 × 10^{-3} N

(c) 9.99 × 10^{-4} N

### QUESTION 5**

There is a point on the x-axis where the electric field is
exactly zero. In which region is this point located?
(a) x > 0

(b) x < -3 m

(c) between x = -3 m and x = 0

### QUESTION 6**

Calculate the y-component of the electric field at (0,
2).
(a) -5.65 × 10^{3} V/m

(b) -3.34 × 10^{3} V/m

(c) 0

(d) +3.34 × 10^{3} V/m

(e) +5.65× 10^{3} V/m

### QUESTION 7*

Calculate the electric potential at (0, 2).
(a) 7.48 × 10^{3} V

(b) 1.73 × 10^{3} V

(c) -1.51 × 10^{3} V

### QUESTION 8***

Calculate the work required to move a +1 mC charge along the y axis from (0,2) to (0,3).
(a) -2.65 × 10^{-3} J

(b) -1.87 × 10^{-3} J

(c) 0

(d) +1.87 × 10^{-3} J

(e) +2.65 × 10^{-3} J

### QUESTION 9*

*This and the next three questions pertain to the following
situation.*
A region in space contains a uniform electric field of E_{x}
= 0 and E_{y} = 2 V/m and no gravitational field. A particle of
mass M = 0.0015 kg and charge Q = -0.005 C is at the origin (0, 0) at
time t = 0, moving to the right (+x direction) with a speed of 2 m/s.

Find the x position of the particle at time t = 4 s.

(a) x = 2 m

(b) x = 8 m

(c) x = 16 m

### QUESTION 10**

Find the y position of the particle at time t = 4 s.
(a) y = -53.3 m

(b) y = -26.6 m

(c) y = -13.3 m

### QUESTION 11***

Calculate the kinetic energy of the particle when it
reaches a point with y = -0.5 m.
(a) 8.00 × 10^{-3} J

(b) 13.3 × 10^{-3} J

(c) 26.0 × 10^{-3} J

### QUESTION 12**

As the particle travels through the field, its electric
potential energy
(a) increases.

(b) remains the same.

(c) decreases.

### QUESTION 13*

*This and the next three questions pertain to the following
situation.*
Two capacitors of C_{1} = 30 µF and C_{2} = 60
µF are connected by a switch to a battery as shown in the figure.
The switch is closed, and capacitor C_{1} acquires a charge
Q_{1}= 1.5 × 10^{-3} C. The switch is then opened
again (as shown).

Calculate the energy stored in capacitor C_{1}.

(a) 1.5 × 10^{-3} J

(b) 3.75 × 10^{-2} J

(c) 7.5 × 10^{-2} J

### QUESTION 14*

Calculate the voltage across C_{2}.
(a) 25 V

(b) 50 V

(c) 75 V

### QUESTION 15*

What is the equivalent capacitance of the pair of
capacitors?
(a) 20 µF

(b) 45 µF

(c) 90 µF

### QUESTION 16***

A material of relative dielectric constant k = 1.5 is now inserted into the charged capacitor
C_{1}. As the dielectric is inserted into capacitor
C_{1} the charge on capacitor C_{1}
(a) increases.

(b) remains the same.

(c) decreases.

### QUESTION 17*

*This and the next question pertain to the following
situation.*
A battery with e = 20 V is used to charge a
capacitor with capacitance C = 5 µF through a resistor R, as shown
in the circuit diagram. The voltage across the resistor R is measured
as a function of time after the switch is closed and the resulting
empirical data is shown below:

How much charge is on the capacitor after a very long time?

(a) 10^{-4} C

(b) 10^{-3} C

(c) 10^{-2} C

### QUESTION 18***

Using the data on the graph above, estimate the value of
the resistance R.
(a) 5 W

(b) 20 W

(c) 40 W

### QUESTION 19*

*This and the next four questions pertain to the following
situation.*
For the first two problems, consider the circuit above with the
switch S open, as shown.

Calculate the equivalent resistance of the circuit.

(a) 2.00 W

(b) 2.08 W

(c) 2.40 W

### QUESTION 20*

Calculate I_{4}.
(a) 2.0 A

(b) 2.5 A

(c) 3.0 A

### QUESTION 21*

**For this and the following two questions, consider the circuit above
with the switch S closed.**
Calculate the equivalent resistance of the circuit.

(a) 2.00 W

(b) 2.08 W

(c) 2.40 W

### QUESTION 22**

What is the electric potential difference between the
switch and the negative side of the battery at point b?
(a) 6 V

(b) 9 V

(c) 15 V

### QUESTION 23***

Calculate I_{S}. (A positive number indicates
current is going in direction shown by arrow in figure.)
(a) -3.0 A

(b) -0.75 A

(c) 0 A

(d) 0.75 A

(e) 3.0 A

### QUESTION 24**

*This and the next two questions pertain to the following
situation.*
In the circuit to the right, the switch has been open for a long time
as shown.

Calculate I_{B}, the current through the battery, immediately
after the switch is closed.

(a) I_{B} = 0.33 A

(b) I_{B} = 0.5 A

(c) I_{B} = 1 A

### QUESTION 25*

Calculate I_{B}, the current through the battery,
after the switch has been closed for a long time.
(a) I_{B} = 0.33 A

(b) I_{B} = 0.5 A

(c) I_{B} = 1 A

### QUESTION 26***

After the switch has been closed for a long time, the
charge on the capacitor is observed to be 15 mC. What is the
capacitance C?
(a) C = 2.25 × 10^{-3} F

(b) C = 1.50 × 10^{-3} F

(c) C = 0.75 × 10^{-3} F

### QUESTION 27*

*This and the next question pertain to the following
situation.*
Eleven positive point charges +Q and one negative charge –Q are
situated on the perimeter of a circle with radius r, as shown in the
figure.

Calculate the magnitude of the electric field at the center of the
circle.

(a) |E| = 0

(b) |E| = 1 k Q / r^{2}

(c) |E| = 2 k Q / r^{2}

(d) |E| = 10 k Q / r^{2}

(e) |E| = 11 k Q / r^{2}

### QUESTION 28*

Calculate the electric potential at the center of the
circle.
(a) V = 0

(b) V = 1 k Q / r

(c) V = 2 k Q / r

(d) V = 10 k Q / r

(e) V = 11 k Q / r

### QUESTION 29*

A set of batteries and resistors is connected as shown
below.