ame: ________________________
Exam 2--PHYS 202--Spring 2011
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
____
____
1. Which of the following equations for this circuit is
correct?
a. -6-8I1-3I3-4I1=0
c. 12-2I2-8I1-6-4I1=0
b. 6-8I1+2I2-12-4I1=0
d. I1+I3=I2
2. Two pieces of copper wire are the same length. The diameter of wire A is twice that of wire B. How do
their resistances compare?
a. RA=RB
d. RA=2RB
b. RA=½RB
e. RA=4RB
c. RA=¼RB
3. Which lightbulb, in your house, draws more current: a 40 W or a 100 W bulb?
a.
b.
40 W
100 W
c.
1
both the same
____
4. The following circuit is relevant for the next 4 questions. What is the equivalent resistance of this circuit?
____
a. 1.0 Ω
c. 1.4 Ω
b. 7.0 Ω
d. 4.0 Ω
5. For the circuit in the previous figure, what is the potential across R 3?
____
a. 5.4 V
d. 3.0 V
b. 4.0 V
e. 12 V
c. 6.0 V
6. For the circuit above, if R 3 is removed from the circuit, what happens to the current through R 1?
____
a. it increases
c. it decreases
b. it remains the same
7. Consider the above circuit. Which resistor has the least current travelling through it?
a.
b.
R1
R3
c.
d.
2
R5
all have the same current
____
8. Which of these statements about a household circuit is true:
I. The household circuit is a parallel circuit.
II. All devices in a household circuit operate at the same current.
III. As you add more devices to a household circuit, the potential across each device
decreases.
IV. The circuit breaker turns off if I in>Iout for any particular device.
____
a. I & II
c. I & IV
b. I
d. II & III
9. Which of these best describes why some materials are permanent magnets (so-called “ferromagnetic”)?
a.
these materials are found in the center of c. these materials are made of metal
the Earth
b. the magnetic domains of these materials d. these materials contain charges
are all aligned in the same direction
____ 10. This figure shows a loop of wire, through which current flows, in the magnetic field of a permanent magnet.
In which direction does the loop initially turn?
a.
b.
clockwise
counter clockwise
c.
d.
3
the loop does not move
there is not enough information
____ 11. A positive charge is travelling towards a wire as shown. Initially, there is no current through the wire. What
direction will the charge travel when the current is turned on?
a.
b.
down
into the page
c.
d.
up
out of the page
____ 12. A negative charge enters a magnetic field as shown. In what direction will it feel a force?
a.
b.
c.
up
down
left
d.
e.
4
into the page
right
____ 13. The point A is equidistance between these two, long parallel wires. What is the direction of the magnetic
field at point A due to the two wires?
a. To the right
d. To the left
b. Into the page
e. There is no magnetic field at A
c. Out of the page
____ 14. These are types of light in the electromagnetic spectrum (listed alphabetically). Arrange them in order from
lowest energy to highest energy:
gamma rays
microwaves
radio waves
ultraviolet
a.
b.
microwaves, ultraviolet, radio, gamma
microwaves, radio, ultraviolet, gamma
c.
d.
5
gamma, radio, microwaves, ultraviolet
radio, microwaves, ultraviolet, gamma
____ 15. This figure shows the path that light travels through 3 different materials. Which of these describes the
relationship between the indices of refraction?
a.
b.
n1>n2<n3
n1<n2>n3
c.
d.
n1<n2<n3
n1>n2>n3
____ 16. In this figure, light travels from water to glass. What must θ1 be for total internal reflection to occur? (The
index of refraction for water is 1.3; the index of refraction for glass is 1.5.)
a. Total internal reflection will not occur.
c. 42°
b. 60°
d. 30°
____ 17. Select the words that best complete this sentence: The 17th century physicist Huygens proposed a theory that
described light as a _________ based on the properties observed in _____________.
a.
b.
c.
wave, photoelectric effect
wave, refraction
wave, interference
d.
e.
6
particle, reflection
duality, diffraction
____ 18. This figure shows an incoming ray that is incident on a right-angle mirror at an angle of θ1=30°. What is the
angle θ2 for the reflected ray? (The figure is not drawn to scale.)
a.
b.
90°
30°
c.
d.
7
60°
15°
Problem
19. (25 pts) Label the currents in this circuit. Calculate each current and give its magnitude and
direction . For extra credit (3 pts), solve the system of equations by creating the identity matrix.
.
8
20. (20 pts) A particle carrying a +2.0 C charge moves with velocity v = 3j - 3k m/s
through
a uniform magnetic field B = 2i - 4j T. What is the force, in vector notation, on the charged
particle?
.
9
21. (15 pts) A LASER ray travels through an aquarium of water as shown in this figure. What is the height from
the floor (y) that the ray strikes the wall above the aquarium? (The index of refraction for water is 1.3.)
.
10
22. (5 pts) Describe, in your own words, how an electric generator works. Be brief (no more than ~25 words).
.
11
ID: A
Exam 2--PHYS 202--Spring 2011
Answer Section
MULTIPLE CHOICE
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
B
C
B
A
C
B
B
B
B
A
A
C
E
D
A
A
B
C
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
PROBLEM
19. ANS:
.
PTS: 1
20. ANS:
.
PTS: 1
21. ANS:
.
PTS: 1
22. ANS:
A coil of wire sits in a magnetic field. When a force is applied to the coil, charges flow through the wire.
PTS: 1
1