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Instructor(s): G. Boyd
PHYSICS DEPARTMENT
EXAM I
PHY2005, Summer 2008
Name (print, last first):
June 4, 2006
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 answer sheet (use lines 76–80 on the answer sheet for the 5-digit number).
Code your name on your answer sheet. DARKEN CIRCLES COMPLETELY. Code your UFID number on your
answer sheet.
(2) Print your name on this sheet and sign it also.
(3) Do all scratch work anywhere on this exam that you like. Circle your answers on the test form. At the end of the
test, this exam printout is to be turned in. No credit will be given without both answer sheet and printout.
(4) Blacken the circle of your intended answer completely, using a #2 pencil or blue or black ink. Do not
make any stray marks or some answers may be counted as incorrect.
(5) Hand in the answer sheet separately.
Constants: e = 1.6 × 10−19 C mp = 1.67 × 10−27 kg me = 9.1 × 10−31 kg c = 3 × 108 m/s
²o = 8.85 × 10−12 C 2 /N · m2
k = 1/(4π²o ) = 9 × 109 N · m2 /C 2
nano = 10−9
micro = 10−6
|q1 ||q2 |
Coulomb’s Law: |F~ | =
(point charge)
4π²o r2
~
~ =F
Electric field: E
q
q
V =
(point charge)
4π²o r
Capacitors: q = CV
~ =
E
C=
1
1
1
=
+
C
C1
C2
Resistors: i =
1
1
1
=
+
R
R1
R2
dq
dt
R=
V
i
q
r̂ (point charge)
4π²o r2
²o A
(parallel-plate)
d
R=
ρL
(wire)
A
C = C1 + C2
P = iV
R = R1 + R2
Choose the best answer provided, i.e. the one closest to your computation.
1. An electron is stopped by potential difference of 60V. What was it’s initial speed in m/s? (hint, kinetic energy).
(1) 4.6 × 106 m/s
(2) 2.1 × 1013 m/s
(3) 3.2 × 106 m/s
(4) 0 m/s
(5) none of these
2. Two conducting spheres have charges +3 C and -4 C and are separated by 25 cm. What is the magnitude of the force
on them?
(1) 1.7 × 1012 N
(2) 3.2 × 1012 N
(3) 1.7 × 108 N
(4) 4.6 × 1010 N
(5) none of these
3. Two conducting spheres have charges +3 C and −4 C. The two spheres are touched, then brought 5m apart. What is
the new force between them?
(1) 9 × 107 N
(2) 7 × 107 N
(3) 4 × 109 N
(4) 1 × 109
(5) none of these
4. A particle ‘weighs’ .510 MeV (=it’s energy). If E = mc2 as Einstein claims, then what does this particle weigh in
kilograms?
(1) 9.1 × 10−31 kg
(2) 3.5 × 107 kg
(3) 2.7 × 10−22 kg
(4) 1.67 × 10−27 kg
(5) none of these
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5. The electric field in a large awesome-looking room is 100 N/C. A charged 3 kg ball hangs from a thread at an angle of
30o from the vertical. Find the charge on the ball.
(1) .042 C
(2) .127 C
(3) .254 C
(4) .08 C
(5) none of these
6. Two protons are held 10−15 m apart, then released. After a long time, what is the velocity of only one of the protons in
m/s?
(1) 1.1 × 107 m/s
(2) 5 × 1014 m/s
(3) 1.6 × 107 m/s
(4) 1.3 × 1014 m/s
(5) none of these
7. Refer to the figure. All the resistors are marked, with their units in
Ohms. Find the equivalent resistance of the network.
(1)
(2)
(3)
(4)
(5)
6.27 Ohms
5.55 Ohms
3.77 Ohms
4.2 Ohms
none of these
8. If a light bulb operates at a voltage 4.5 V and has a resistance of 8 Ohm, how much charge passes through the bulb
filament in 2 seconds?
(1) 1.02 C
(2) .56 C
(3) 3.5 × 1018 C
(4) 1.8 × 1019 C
(5) none of these
9. Refer to the figure. Find the Current in the 6 Ohm resistor (magnitude
only, sign doesnt matter)?
(1)
(2)
(3)
(4)
(5)
.434 Amps
.086 Amps
.563 Amps
1.32 Amps
none of these
10. Refer to the figure in the previous question. What is the power dissipated by the 6 ohm resistor?
(1) 1.13 Watts
(2) 5 Watts
(3) .56 Watts
(4) .044 Watts
(5) none of these
11. Three capacitors with 2µF are connected in series then to a battery of 4 V. What is the charge stored in the circuit?
(1) 2.66µC
(2) 4µC
(3) .166µC
(4) 6µC
(5) none of these
12. Three capacitors with 3µF are connected in parallel then to a battery of 6 V. What is the charge stored in the system?
(1) 36µC
(2) 6µC
(3) 1.666µC
(4) 1.5µC
(5) none of these
THE FOLLOWING QUESTIONS, NUMBERED IN THE ORDER OF THEIR APPEARANCE ON THE ABOVE
LIST, HAVE BEEN FLAGGED AS CONTINUATION QUESTIONS: 10