ame: ________________________ Class: ___________________ Date: __________
Exam 4--PHYS 202--S14
Multiple Choice
Identify the choice that best completes the statement or answers the question.
1. A positively charged particle enters a magnetic
field as shown. What is the force acting on the
particle?
3. If the particle in the mass spectrometer is traveling
as in this figure. What is the direction of the initial
force on the particle?
a. up
b. down
c. left
d. right
e. out of the page
4. The magnetic pole of the Earth nearest the
geographic North Pole corresponds to which of the
following?
a. a magnetic north pole
b. a magnetic antarctic pole
c. a magnetic south pole
d. a magnetic arctic pole
5. A positive charge approaches a wire with a current
of 1A flowing within it. The charge is deflected to
the left as in this figure. What is the direction of
the current?
a. into the page
b. out of the page
c. left
d. right
e. down
2. Which of these statements is true?
I. Magnets have only a north or south pole
II. North poles of a magnet attract.
III. Wood is ferromagnetic
a.
b.
c.
d.
e.
I & II
II & III
II
all of these are true
none of these are true
a.
b.
c.
1
left
right
there is no current
ame: ________________________
8. Organize these types of radiation in order of
shortest wavelength to longest wavelength:
6. Consider the light ray as it travels through the 2
media. Which of these statements is true?
Gamma
Radio
Ultraviolet
Visible
a. n1>n2
b. n1=n2
c. n1<n2
d. Not enough information
7. Consider this arrangement of mirrors. What is the
angle of reflection off of mirror #2?
a.
b.
c.
d.
e.
a. Gamma, Ultraviolet, Visible, Radio
b. Radio, Visible, Ultraviolet, Gamma
c. Ultraviolet, Visible, Radio, Gamma
d. Gamma, Visible, Ultraviolet, Radio
9. Newton explained light as a ______ because of
_____; Huygens explained light as a ____ because
of ____.
a. particle, reflection; wave, interference
b. particle, refraction; wave, interference
c. wave, interference; particle, photoelectric
effect
d. particle, reflection; wave, refraction
10. The index of refraction is dependent on wavelength
as shown in this figure. When white light passes
through a prism, which color will be bent or
refracted the most?
90°
50°
80°
40°
10°
n=1.53
Glass
Index
of
Refraction
n=1.51
λ=400 nm
λ=700 nm
Wavelength
a.
b.
c.
d.
2
red
orange
green
blue
ame: ________________________
Problem
11. (20 pts) Fiber optic cables consist of a plastic or glass core surrounded by a cladding with a lower index of
refraction. Engineers describe the range of angles of incidence for which total internal reflection will occur as the
acceptance cone.
a) What would happen if the cladding had an index of refraction higher than that of the core?
b) What is the angle, θ, subtended by the by the acceptance cone?
c) What is the speed of light within the core of this fiber optic cable?
d) Estimate the time required for a light signal to travel 1000 m of fiber optic cable. (Assume a straight-line path.)
3
ame: ________________________
12. (20 pts) A positive particle moves into the B-field of a mass spectrometer; the particle is moving at a speed of 2
m/s. The magnetic field has a magnitude of 2.0 T, and the radius of the particle’s path is 0.5 m. Following is a
table with the masses and charges of some imaginary particles.
a) Which of these is this unknown particle? (Show all calculations.)
b) What is the magnitude of the electric field that must be applied to the charged particle so that it will move in a
straight line?
c) Describe, in 20 words or less, how a mass spectrometer works.
4
ame: ________________________
13. (20 pts) Consider this loop of wire. There is a current of 3A through the wire, and it sits inside a uniform magnetic
field as shown.
a) Give the force on the left side of the loop in vector notation.
b) Label the direction of the forces on both sides of the loop.
c) What is the magnitude of the net torque on the loop? (Hint: τ = F ⊥ r. Disregard the force on the 0.2 m ends of
the loop; the torque due to those wires is neglible.)
5
ame: ________________________
14.
(10 pts) A 2C charge has an initial velocity of (2j8 − 3k8) m / s in a region in which a
uniform magnetic field is present. If ä
B = (10i8)T , give the net force, in vector
notation, on the particle.
6
ID: A
Exam 4--PHYS 202--S14
Answer Section
MULTIPLE CHOICE
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
B
E
B
C
B
C
E
A
D
D
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
1
1
1
1
1
1
1
1
1
1
DIF: 1
TOP: 19.1 Magnets
PROBLEM
11. ANS:
.
PTS: 1
12. ANS:
.
PTS: 1
13. ANS:
.
PTS: 1
14. ANS:
.
PTS: 1
1