Practice Test 2
1.
Determine the charge stored by C1 when C1 = 20 µF, C2 = 10 µF,C3 = 30 µF, and V0 = 18 V.
a.
b.
c.
d.
e.
0.37 mC
0.24 mC
0.32 mC
0.40 mC
0.50 mC
b
2.
What is the magnitude of the potential difference across the 20- resistor?
a.
b.
c.
d.
e.
3.2 V
7.8 V
11 V
5.0 V
8.6 V
b
3.
What is the equivalent resistance between points a and b when R = 13 ?
a.
b.
c.
d.
e.
29 
23 
26 
20 
4.6 
d
4.
At t = 0 the switch S is closed with the capacitor uncharged. If C = 40 µF,  = 50 V, and R
= 5.0 k, how much energy is stored by the capacitor when I = 2.0 mA?
a.
b.
c.
d.
e.
c
20 mJ
28 mJ
32 mJ
36 mJ
40 mJ
5.
A parallel plate capacitor of capacitance C0 has plates of area A with separation d
between them. When it is connected to a battery of voltage V0, it has charge of
magnitude Q0 on its plates. It is then disconnected from the battery and the plates are
pulled apart to a separation 2d without discharging them. After the plates are 2d apart,
the magnitude of the charge on the plates and the potential difference between them are
a.
b.
c.
d.
e.
1
1
Q0, V0
2
2
1
Q0, V0
2
Q0, V0
Q0, 2V0
2Q0, 2V0
d
6.
A 30-µF capacitor is charged to 80 V and then connected across an initially uncharged
capacitor of unknown capacitance C. If the final potential difference across the 30-µF
capacitor is 20 V, determine C.
a.
b.
c.
d.
e.
60 µF
75 µF
45 µF
90 µF
24 µF
d
7.
A 3.0-µF capacitor charged to 40 V and a 5.0-µF capacitor charged to 18 V are connected
to each other, with the positive plate of each connected to the negative plate of the other.
What is the final charge on the 3.0-µF capacitor?
a.
b.
c.
d.
e.
a
11 µC
15 µC
19 µC
26 µC
79 µC
8.
Determine the equivalent capacitance of the combination shown when C = 45 µF.
a.
b.
c.
d.
e.
28 µF
36 µF
52 µF
44 µF
23 µF
b
9.
A nichrome wire and an aluminum wire, each with the same initial resistance, have the
same change in resistance when heated separately. (  Al  2.82 108   m ;
 Al  3.9 103/C ;  nichrome  1.50 106   m ;  nichrome  0.40 103/C .) The ratio of the
temperature change of the nichrome wire to the temperature change of the aluminum
wire is
a.
b.
c.
d.
e.
0.019.
0.10.
0.18.
9.8.
53.
d
10.
What is the resistance of a wire made of a material with a resistivity of 3.2 108  m if
its length is 2.5 m and its diameter is 0.50 mm?
a.
b.
c.
d.
e.
0.16 
0.10 
1.28 
0.41 
0.81 
d
12.
How many electrons pass through a 20- resistor in 10 min if there is a potential drop of
30 volts across it?
a.
b.
c.
d.
e.
5.6  1021
7.5  1021
9.4  1021
1.1  1021
3.8  1021
a
13.
A light bulb is rated at 30 W when operated at 120 V. How much charge enters (and
leaves) the light bulb in 1.0 min?
a.
b.
c.
d.
e.
17 C
15 C
14 C
13 C
60 C
b
14.
Determine the magnitude and sense (direction) of the current in the 10- resistor when I
= 1.8 A.
a.
b.
c.
d.
e.
1.6 A right to left
1.6 A left to right
1.2 A right to left
1.2 A left to right
1.8 A left to right
a
15.
If  1 = 4.0 V,  2 = 12.0 V, R1 = 4 , R2 = 12 , C = 3 µF, Q = 18 µC, and I = 2.5 A, what is
the potential difference Va – Vb?
a.
b.
c.
d.
e.
–30 V
30 V
5.0 V
–5.0 V
–1.0 V
a
16.
The circuit below contains three 100 watt light bulbs. The emf  = 110 V. Which light
bulb(s) is(are) the brightest?
a.
b.
c.
d.
e.
A
B
C
B and C
All three are equally bright.
a
17.
When a capacitor is fully charged, the current through the capacitor is
a.
b.
c.
d.
e.
zero.
at its maximum value.
equal to the current in a resistive circuit in parallel with the capacitor circuit.
greater than the current in a resistor that is farther from the battery than the
capacitor.
zero if it is the only capacitor, but maximum if there is another capacitor in series
with it.
a
18.
A circuit consists of 2N resistors, all of resistance R, connected as shown below. A
potential difference V is applied to one end, and the other end is at ground potential.
The equivalent resistance of the circuit is
V
…..
a.
b.
c.
d.
e.
R
.
2
R.
NR
.
2
NR .
2NR .
c
19.
What is the potential difference Vb – Va shown in the circuit below.
a.
b.
c.
d.
e.
–8.0 V
+8.0 V
–18 V
+18 V
–12 V
a
20.
What is the equivalent resistance between points A and B in the figure when R = 20 ?
a.
b.
c.
d.
e.
77 
63 
70 
84 
140 
c
21.
If Q = 350 µC and I = 4.0 mA in the circuit segment shown below, determine the
potential difference, VA – VB.
a.
b.
c.
d.
e.
d
–30 V
+80 V
+40 V
–40 V
+10 V