ame: ________________________
Exam 1--PHYS 202--S12
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
____
____
1. Which of these statements is true about charging by induction?
a.
b.
it can only occur with protons
it causes a bigger charge than charge by
conduction
2. Look at this kid. What is her problem?
c.
d.
a.
the back of her head is positively charged c.
a.
b.
positive
negative
it can not be done to conductors
it does not require contact between two
charged objects
she has an excess of negative charges in
her hair
b. the day is really, really humid
d. all of the negative charges on her head
have moved to the ends of her hair
3. A charged particle sits in an electric field as shown here. If the particle moves in the direction of dashed line
(to the left), what is the charge of the particle?
c.
d.
1
neutrally charged
You must know the magnitude of the
E-field to know the sign of the charge.
____
____
4. The following figure shows equipotential lines for a configuration of charges. Which charge has the greater
magnitude?
a. the positive charge
c. both have the same magnitude
b. the negative charge
d. there is not enough information
5. The following is a plot of potential (V) versus position (x). You release a proton at the point x=A. What will
the particle do?
a.
b.
remain stationary
go to the right
c.
d.
2
go to the left
oscillate back and forth
____
6. What is the equivalent capacitance of this circuit?
____
a. 12 µF
c. 0.6 µF
d. 0.5 µF
b. 5 µF
7. What is the potential and electric field at the point P, which is in the center of this square?
a.
b.
E≠0, V=0
E≠0, V≠0
c.
d.
3
E=0, V=0
E=0, V≠0
____
8. What is the voltage across C 1, the 2 µF capacitor?
____
a. 12 V
c. 6 V
b. 3 V
d. 4 V
9. You charge a capacitor with a battery of 10 V. Then you remove the battery, so the charge remains constant.
Then you double the distance between the plates of the capacitor. What is the new voltage across the
capacitor?
a. 10 V
b. 5 V
____ 10. What is the primary purpose of a capacitor?
c.
d.
100 V
20 V
a. to create a current
c. to complete a circuit
b. to store electrical energy
d. to create a potential difference
____ 11. You wish to measure the potential difference across a resistor. How do you hook up the device?
a.
b.
in series with the resistor
in parallel with the resistor
c.
d.
replace the resistor with the device
you can’t measure the potential
difference across a resistor.
____ 12. Which has a bigger resistance, a hair dryer (1000 W) or a light bulb (100 W)?
a.
b.
not enough info to tell
both the same
c.
d.
4
hair dryer
light bulb
____ 13. Consider this circuit. What is the current through the resistor?
a. 12 A
c. 48 A
b. 0.16 A
d. 0.08 A
____ 14. The rate for electricity charged by Entergy is $0.05 per kilowatt-hour. How much does it cost you to run
your 1000 W electric heater for 2 hours?
a. $4
b. $0.40
____ 15. Which of these best describes an ammeter?
a.
b.
it measures voltage
it has a very small resistance
c.
d.
$100
$0.10
c.
d.
it is hooked up in parallel with a resistor
it has a very high power rating
5
Problem
16. (20 pts) a) What is the electric field in vector notation at the point ( 0.0 i + 2.0 j+1.0 k) meters if the
electric potential is given by V = 3xz − 2y 2 + 4x 2 yz , where V is in volts and x, y, and z are in meters?
What is the magnitude and direction of the force on a +2 C charge located at this position?
.
6
17. (10 pts) Consider these charged at the vertices of a right triangle.
What are the magnitude and direction of the force acting on particle 2, which has a charge of 2 × 10 −4 C ?
7
18. (15 pts) Consider this configuration of charges:
a) What is the potential at the location of q 2, the +1µC charge?
b) What is the total work required to assemble the charges?
.
8
19. (25 pts) Find the equivalent capacitance and the voltage and charge for each capacitor.
V 1=
Q1=
V 2=
Q2=
V 3=
Q3=
V 4=
Q4=
V 5=
Q5=
V 6=
Q6=
V 7=
Q7=
Ceq=
9
ID: A
Exam 1--PHYS 202--S12
Answer Section
MULTIPLE CHOICE
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
D
C
B
A
C
B
B
C
D
B
B
D
A
D
B
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
PROBLEM
16. ANS:
.
PTS: 1
17. ANS:
.
PTS: 1
18. ANS:
.
PTS: 1
19. ANS:
.
PTS: 1
1