77777
77777
PHYSICS DEPARTMENT
PHY 2005
Makeup Test
Name (print):
April 15, 2009
Signature:
On my honor, I have neither given nor received unauthorized aid on this examination.
YOUR TEST NUMBER IS THE 5-DIGIT NUMBER AT THE TOP OF EACH PAGE.
(1) Code your test number on your pink answer sheet (use 76–80 for the 5-digit number). Code your name
on your answer sheet. Darken circles completely. Code your UF ID number on your answer sheet.
(2) Print your name on this sheet and sign it also.
(3) You will receive one point for each correct answer and zero points for an incorrect answer or no answer.
(4) Use a number 2 pencil on the answer sheet. Do not make any stray marks, or the answer sheet may not be read
properly.
(5) “X” is never the correct answer.
Useful Equations:
1 N = 1 kg m/ s2
1 J = 1 N m = 1 kg m2 / s2
1 W = 1 J/s
1 V = 1 J/ C
1 F = 1 C/ V
1 A = 1 C/ s
k = 1/4π²0 = 9×109 N m2 / C2
²0 = 9×10−12 C2 / N m2
µ0 = 4π×10−7 T m/ A
c = 3×108 m/s2
e = 1.6×10−19 C
λf = c
F~ = m~a
W = F~ · d~
K.E. =
~
F~ = q E
P.E. = qV
F =
kq1 q2
r2
1
mv 2
2
dW
= P = iV = i2 R = V 2 /R
dt
1
1
1
1
=
+
+
Ceff
C1
C2
C3
1
1
1
1
=
+
+
Reff
R1
R2
R3
V = iR
q =VC
C = ²0 A/d
Ceff = C1 + C2 + C3
R = ρL/A
Reff = R1 + R2 + R3
Intensity = P/A
~ = µ0 ni
|B|
~ = µ0 i/2πr
|B|
~ = i`B sin θ
F~ = i~` × B
~ = qvB sin θ
F~ = q~v × B
m
φB = B⊥ A
Einduced = −N
ES = EP
∆φB
∆t
NS
NP
v2
= qvB
r
|E| = Bwv
w stands for “width”
1
for AC Erms = √ Emax
2
1. On your pink answer sheet, did you correctly bubble in your test number in rows 76–80, and also bubble in your name
and your UF ID number (not your social security number!)? Also, did you print and sign your name at the top of your
test, and will you hand in the “white sheets?” before leaving the room? This question counts, and the correct answer
is “Yes”, unless you erred in filling out the pink answer sheet.
(1) Yes
(2) X
(3) X
(4) X
(5) X
2. Which is closest to the number of electrons in a Coulomb?
(1) 6×1018
(2) 6×1017
(3) 6×1019
(4) 6×1021
(5) 6×1023
77777
77777
3. Initially two identical, small conducting spheres have different charges. Sphere A has charge qA = 7 C, and sphere B
has an unknown charge qB . Next, the two spheres are brought together so that they touch. Later, they are separated
again and the charge on A is then −11 C. What was the initial charge on B?
(1) −29 C
(2) −11 C
(3) −18 C
(4) −7 C
(5) −15 C
4. In Figure B, we have three small, charged objects. The charge q1 = 1 C, but q2 and q3 are unknown. When q1 and
q2 are separated by 1 m the force is attractive and has a magnitude of 6 N. When q2 and q3 are separated by 1 m the
force is repulsive and has a magnitude of 3 N. What is the charge q3 ?
1
(1) − C
2
(2) −2 C
1
(4) − C
3
(3) 2 C
(5) Not enough information
5. Two charges q1 and q2 are separated by a distance 4 m and the force between them has a magnitude of 8 N. Which is
closest to the magnitude of the force if the charges were separated by 12 m?
(1) 0.89 N
(2) 0.67 N
(3) 2.67 N
(4) 1.33 N
(5) 0.067 N
6. A 1 F capacitor and a 2 F capacitor are arranged in a series circuit with a 6 V battery and a switch as shown in Figure
A. Initially, the capacitors are not charged and the switch is open. Then, the switch is closed. Now, what is the charge
q1 on the 1 F capacitor?
(1) 4 C
(2) 2 C
(3) 3 C
(4) 6 C
(5) 8 C
7. With the same arrangement as in Figure A with the switch closed, what is the potential drop across the 2 F capacitor?
(1) 2 V
(2) 4 V
(3) 1 V
(4) 3 V
(5) 6 V
8. A 6 V battery is attached to a capacitor which holds 4 C when the separation between the capacitor plates is 2 cm.
What would the charge on the capacitor be if the separation were changed to 1 cm?
(1) 8 C
(2) 16 C
(3) 4 C
(4) 2 C
(5) 1 C
9. A demonstration involved two polaroid filters and the overhead projector. At one time, the two filters were oriented
so that the light on the screen was at its brightest. Then the top filter was slowly rotated until the light on the screen
was at its dimmest. What was the angle of the rotation?
(1) 90◦
(2) 180◦
(3) 45◦
(4) 30◦
(5) 60◦
10. One day in class, you were asked to go home, stand 2 feet away from a mirror and mark a circle on the mirror that
just surrounded the image of your face on the mirror. Next, you were to step back and double the distance to 4 feet.
As you looked at your face in the mirror then, how did its size on the mirror compare to the size of t original outline?
(1)
(2)
(3)
(4)
(5)
Face same size as outline.
Face smaller than outline.
Face larger than outline.
Face disappeared.
Mirror was too foggy to see.
11. An electron is moving with a constant speed v in a circle, perpendicular to a uniform magnetic field. The radius of the
circle is initially 4 m. Suddenly the electron bounces off a proton and its speed doubles, but it still moves in a circle
perpendicular to the magnetic field. Now, what is the radius of the circle?
(1) 8 m
(2) 2 m
(3) 4 m
(4) 1 m
(5) 16 m
77777
77777
12. A large current in a wire comes directly out of the paper in Figure C. At which spot would the poles of a small compass
match the letters N and S? Assume that the Earth’s magnetic field is too small to be important in this problem.
(1) b
(2) a
(3) c
(4) d
(5) none
13. The local radio station “Classic 89” broadcasts at approximately 90 MHz = 9×107 Hz. Which is closest to the wavelength of these radio waves?
(1) 3 m
(2) 3 cm
(3) 3 mm
(4) 3 km
(5) 3 nm
14. A DC power supply provides an Emf of 10 V and is hooked up in series with a 2Ω resistor. Which is closest to the
average power loss in the resistor?
(1) 50 W
(2) 20 W
(3) 25 W
(4) 10 W
(5) 5 W
15. An AC power supply provides a maximum Emf of 10 V and is hooked up in series with a 2Ω resistor. Which is closest
to the average power loss in the resistor? Hint: This problem differs from the previous one. The answer might, or
might not, be different.
(1) 25 W
(2) 20 W
(3) 50 W
(4) 10 W
(5) 5 W
THE FOLLOWING QUESTIONS, NUMBERED IN THE ORDER OF THEIR APPEARANCE ON THE ABOVE
LIST, HAVE BEEN FLAGGED AS CONTINUATION QUESTIONS: 7 15