This exam consists of 31 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 94. When the exam was given, the mean was
73.6; the median was 70. Click here to see
page1 page2
of the formula sheet that came with the exam.

What is the force required at time t = 0.5 s to maintain this
velocity?

(a) 0

(b) 1.0 × 10^{-5} N

(c) 4.0 × 10^{-5} N

### QUESTION 6***

What is the force required at time t = 3 s to maintain this
velocity?
(a) 0

(b) 1.0 × 10^{-5} N

(c) 4.0 × 10^{-5} N

### QUESTION 7**

What is the power dissipation in the coil at time t = 2.0
s?
(a) 0

(b) 1.0 × 10^{-7} W

(c) 2.0 × 10^{-7} W

(d) 4.0 × 10^{-7} W

(e) 8.0 × 10^{-7} W

### QUESTION 8**

In which direction will the induced current flow through
the loop at time t = 2.0 s?
(a) clockwise

(b) counterclockwise

### QUESTION 9*

*This and the following question pertain to the following
situation.*
An electron (charge = -1.67 × 10^{-19} C, mass = 9.11
× 10^{-31} kg) with velocity v = 4.6 ×
10^{6} m/s to the right enters a box 0.5 meters wide with a
uniform magnetic field pointing into the page.

What is the direction of the magnetic force on the negatively charged
particle when it first enters the box?

(a) downward

(b) upward

### QUESTION 10*

What is the minimum magnetic field B necessary to keep the
particle from hitting the far side of the box?
(a) 6.28 × 10^{-6} T

(b) 1.26 × 10^{-5} T

(c) 5.02 × 10^{-5} T

### QUESTION 11**

Which element in this AC circuit has the largest peak voltage
across it?
(a) R

(b) L

(c) C

(d) generator

(e) none of the above

### QUESTION 12*

*This and the next two questions pertain to the
following situation.*
Two parallel wires, each with length L = 5 m, are separated by a
distance of 0.05 m. Wire 1 carries a current I_{1} = 15 A, and
wire 2 carries a current I_{2} = 25 A, both in the same
direction.

What is the magnitude of the magnetic field due to wire 1 at the
center of wire 2 ?

(a) 6.0 × 10^{-5} T

(b) 0.9 × 10^{-4} T

(c) 1.5 × 10^{-4} T

### QUESTION 13*

What is the magnetic force acting on wire 2.
(a) 4.5 × 10^{-3} N

(b) 7.5 × 10^{-3} N

(c) 1.25 × 10^{-2} N

### QUESTION 14*

Is the force between the two wires attractive or
repulsive?
(a) attractive

(b) repulsive

### QUESTION 15*

*This and the following two questions pertain to the following
situation.*
A solenoid with cross sectional area A = 4 cm^{2} is 120 cm
long and has 2500 turns. The magnetic field at the center of the
solenoid is 5 × 10^{-3} T __pointing into the page__.
A square wire loop 1.5 cm on each side is fixed inside the solenoid as
shown.

What is the direction of the current through the coils of the
solenoid?

(a) clockwise

(b) counterclockwise

### QUESTION 16*

What is the magnitude of the current through the coils of
the solenoid?
(a) 1.28 A

(b) 1.59 A

(c) 1.91 A

### QUESTION 17**

The current in the solenoid is uniformly decreased to 1/2 its
previous value over 5 seconds. What is the magnitude of the induced emf
in the square loop?
(a) 1.1 × 10^{-7} V

(b) 7.5 × 10^{-7} V

(c) 1.8 × 10^{-3} V

### QUESTION 18**

*This and the following question pertain to the following
situation.*
A conducting wire loop is being manually rotated, at constant w = 30 rad/s. At the instant shown, side AC is
coming out of the page, and side BD is going into the page. There is a
constant magnetic field B = 0.4 T pointing to the right as shown and the
loop has resistance 5 W.

At the instant shown, the induced current in the loop will flow

(a) clockwise.

(b) counterclockwise.

(c) No current is induced.

### QUESTION 19**

What is the induced current at the moment the loop has
rotated 45° from the position shown?
(a) 0 A

(b) 3.4 A

(c) 4.8 A

### QUESTION 20**

*This and the following two questions pertain to the following
situation.*
A generator is hooked up to a transformer with N_{P} = 300,
N_{S} = 1500, as shown (but not to scale). The generator
produces voltage V(t) = (200 V) sin (2pt)
across the primary of the transformer.

What is the period of the oscillating voltage in the secondary
circuit?

(a) 0.159 s

(b) 1 s

(c) 6.28 s

### QUESTION 21*

What is the rms voltage across the secondary?
(a) 28.3 V

(b) 40 V

(c) 707 V

### QUESTION 22**

Compare I_{p}, the peak current through the primary
with I_{s}, the peak current through the secondary.
(a) I_{p} > I_{s}

(b) I_{p} = I_{s}

(c) I_{p} < I_{s}

### QUESTION 23*

The tuner of a radio involves an RLC circuit with a fixed
value inductor but with a variable capacitor. After listening to the
station 107.1 MHz for a while, you now tune in to another radio station
at 97.3 MHz. Does the value of the capacitor in the radio increase or
decrease as you change the station?
(a) C decreases.

(b) C increases.

### QUESTION 24*

*This and the following question pertain to the following
situation.*
Initially unpolarized light is incident on a series of two linear
polarizers.

If the initial intensity of the incident (unpolarized) light is
I_{0}, what is the intensity I_{2} transmitted by the
stack?

(a) I_{2} = 0.015 I_{0}

(b) I_{2} = 0.0301 I_{0}

(c) I_{2} = 0.48 I_{0}

### QUESTION 25***

If the magnetic field amplitude after passing through the
first polarizer is B_{1}, then what is the amplitude after
passing through the second polarizer?
(a) B_{2} = 0.0251 B_{1}

(b) B_{2} = 0.1736 B_{1}

(c) B_{2} = B_{1}

### QUESTION 26*

*This and the following question pertain to the following
situation.*
Electromagnetic waves of frequency 4 × 10^{6} Hz and
average energy density 4 × 10^{-6} J/m^{3} are
incident upon a panel of area 10 m^{2}.

What is the wavelength of these waves?

(a) 1.33 × 10^{-2} m

(b) 75 m

(c) 1.2 × 10^{15} m

### QUESTION 27*

How much energy is transmitted through the panel in a
period of 10 s?
(a) 4 × 10^{-4} J

(b) 1.2 × 10^{5} J

(c) 3 × 10^{15} J

### QUESTION 28*

*This and the following three questions pertain to the following
situation.*
The phasor diagram shown gives information on a particular series RLC
circuit. It is only partially labeled, but you should know from
examining it the proper quantity that is referred to by each number.
The maximum voltage supplied by an AC power source of unknown frequency
is 100 volts.

What is the total impedance?

(a) 1 W

(b) 3 W

(c) 5 W

### QUESTION 29*

What is the peak voltage across the capacitor?
(a) 20 V

(b) 60 V

(c) 100 V

### QUESTION 30**

What is the average power delivered by the generator?
(a) 600 W

(b) 1000 W

(c) 3333 W

### QUESTION 31*

The voltage across the generator is _________ the current
through it?
(a) leading

(b) in phase with

(c) lagging

**Scoring of True-False (T,F) Questions:**
- If you mark the correct answer, you get 2 points.
- If you mark the wrong answer or if you mark neither answer, you get 0 points.

**Scoring of Multiple Choice I (a,b,c) Questions:**
- If you mark the correct answer, you get 3 points.
- If you mark a wrong answer or if you mark none of the answers, you get 0 points.

**Scoring of Multiple Choice II (a,b,c,d,e) Questions:**
- If you mark one answer and it is the correct answer, you get 6 points.
- If you mark two answers and one of them is the correct answer, you get 3 points.
- If you mark three answers and one of them is the correct answer, you get 2 points.
- If you do not mark the correct answer, or if you mark more than three answers,
or if you mark none of the answers, you get 0 points.