variable.
9. Two areas of application of the concepts covered in this chapter are
the TV picture tube and electricity billing procedure.
REVIEW QUESTIONS
1.1
One millivolt is one millionth of a volt.
(a) True
(b) False
1.2
The prefix micro stands for:
(a) 106
(b) 103
(c) 10−3
1.3
(d) 10−6
The voltage 2,000,000 V can be expressed in powers
of 10 as:
(a) 2 mV (b) 2 kV
(c) 2 MV (d) 2 GV
1.4
A charge of 2 C flowing past a given point each
second is a current of 2 A.
(a) True
(b) False
1.5
A 4-A current charging a dielectric material will
accumulate a charge of 24 C after 6 s.
(a) True
(b) False
1.6
Voltage is measured in:
(a) Watts
(c) Volts
|
▲
|
▲
1.7
The unit of current is:
(a) Coulomb
(c) Volt
1.8
The voltage across a 1.1 kW toaster that produces a
current of 10 A is:
(a) 11 kV (b) 1100 V
(c) 110 V (d) 11 V
1.9
Which of these is not an electrical quantity?
(a) charge
(b) time
(c) voltage
(d) current
(e) power
1.10
The dependent source in Fig. 1.19 is:
(a) voltage-controlled current source
(b) voltage-controlled voltage source
(c) current-controlled voltage source
(d) current-controlled current source
io
vs
+
!
6io
(b) Ampere
(d) Joule
Figure 1.19
(b) Amperes
(d) Joules per second
For Review Question 1.10.
Answers: 1.1b, 1.2d, 1.3c, 1.4a, 1.5a, 1.6b, 1.7c, 1.8c, 1.9b, 1.10d.
e-Text Main Menu| Textbook Table of Contents |Problem Solving Workbook Contents
amounts of electrons:
(a) 6.482 × 1017
(b) 1.24 × 1018
19
(c) 2.46 × 10
(d) 1.628
1020Concepts
CHAPTER
1 ×Basic
0
0
Figure 1.20
2
4
6
8
2
4
For Prob. 1.6.
10
12
6
23
Find the energy absorbed by the element in 2 s.
t (ms)
8
t (s)
1.11
!50
Find the current flowing through an element if the
charge flow is given by:
CHAPTER 1
Basic Concepts
23
(a) q(t) = (t + 2) mC
PROBLEMS
Figure 1.21 For Prob. 1.7.
1.7
The charge flowing in a wire is plotted in Fig. 1.21.
(b) q(t) = (5t 2 + 4t − 3) C
Sketch
the corresponding current.
−4t
q
(C)
Section 1.3
Charge(c)
and
Current
q(t)
= 10e pC
P R O B L E M S (d) q(t) = 20 cos 50π t nC
1.8
The
current flowing past a point in a device is shown
50
1.1
How many coulombs are represented by these
in Fig. 1.22. Calculate the total charge through the
−2t
q (C) point.
= 5e and
sinCurrent
100t µC
amounts
of electrons:
Section
1.3 (e) q(t)
Charge
17
18
(a) 6.482
×
10
(b)
1.24
×
10
0
|
1.1 1.3
How
many
represented
by these
Find coulombs
the chargeare
q(t)
flowing
through
a device| if the | 2 50 4
19
20
8 t (s)
6
(c) 2.46 × 10amounts
(d)
i (mA)
of electrons:
current
is: 1.628 × 10
1.3
1.4
1.5
1.6
q(t) (mC)
Figure 1.20
80
q(t) (mC)
80
For Prob. 1.6.
0
Figure 1.23
1.11 5 The voltage v across a device and the current i
2 through
3
it4are 5 t (s)
1
v(t) = 5 cos 2t V,
For Prob.
0 1.9.1
2
3
4
i(t) = 10(1 − e−0.5t ) A
5 t (s)
|
▲
Calculate:
Sections
1.4
and
1.5
Voltage,
Power,
and
(a)
theFor
total
charge
1.7
The charge flowing in a wire is plotted in Fig. 1.21.
Figure 1.23
Prob.
1.9. in the device at t = 1 s
Energy
Sketch the corresponding current.
(b) the power consumed by the device at t = 1 s.
Sections
1.4 and
1.5draws the
Voltage,
1.10
A certain
electrical
element
currentPower, and
i(t) = 10 cos 4t A at a voltage v(t)Energy
= 120 cos 4t V.
0
2
4
6
8 10 12 t (ms)
Find the energy absorbed by the element in 2 s.
1.10
A certain electrical element draws the current
1.11
The voltage vi(t)
across
a device
and
currentv(t)
i = 120 cos 4t V.
= 10
cos 4t A
at the
a voltage
Figure 1.20 For Prob. 1.6.
0
2
4
6
8 10 12 t (ms)
through it areFind the energy absorbed by the element in 2 s.
|
v(t) = 5 cos 2t V,
i(t) = 10(1 − e−0.5t ) A
Calculate:
(a) the total charge in the device at t = 1 s
(b) the power consumed by the device at t = 1 s.
e-Text Main Menu Textbook Table of Contents |Problem Solving Workbook Contents
17
18
(a) flowing
6.482
10=
(b)
(a) ×
i(t)
3 A,
= 11.24
10
0
!50
Find the current
through
an q(0)
element
ifCthe× 10 20
19
2
4
8 t (s)
6
2.46
×i(t)
10 = (2t + 5) (d)
(b)
mA,1.628
q(0) ×
= 10
0
charge flow is(c)
given
by:
(c) i(t) = 20 cos(10t + π/6) µA, q(0) = 2 µC
(a) q(t)
+ 2)the
mC
!50
1.2 = (t Find
current flowing
through an element if the Figure 1.21 For
Prob. 1.7.
2
(d)
i(t)C= 10e−30t sin 40t A, q(0) = 0
(b) q(t) = (5tcharge
+ 4tflow
− 3)
is given by:
0
2 t (ms)
1
−4t
(c) q(t) = 10e
pC
(a) q(t)
= current
(t + 2) flowing
mC
1.4
The
through a device 1.8
is
The current flowing
past a For
point
in a1.7.
device is shown
Figure 1.21
Prob.
(d) q(t) = 20(b)
cosq(t)
50πt
i(t)
=
6π−
t A.
the total charge flow
Figure
For Prob.
1.8. the
=nC
(5t52 sin
+ 4t
3) Calculate
C
in Fig. 1.22. Calculate
the1.22
total charge
through
−2t
the pC
device from t = 0 to t = 10 ms. point.
(e) q(t) = 5e(c) q(t)
sinthrough
100t
µC−4t
= 10e
1.8
The current flowing past a point in a device is shown
1.9
The current through an element is shown in Fig.
(d)q(t)
q(t)
= 20 cos
50πt
nC
1.5
Determine
the
total
chargeifflowing
into an element
Find the charge
flowing
through
a device
the
in Fig. 1.22. Calculate the total charge through the
1.23. Determine the total charge that passed through
for=05e
<−2t
t<
s when
sin2100t
µCthe current entering its i (mA)
current is: (e) q(t)
point.
−2t
the element at:
positive
terminal
is
i(t)
=
e
mA.
(a) i(t)
q(0)
1 C q(t) flowing through a device if the
10
1.3 = 3 A,
Find
the=charge
(a) t = 1 s
(b) t = 3 s
(c) t = 5 s
(b) i(t) = (2t
+ 5) mA,
q(0) =entering
0
1.6
The
a certain element is shown in
i (mA)
current
is: charge
1.20.
Find=
the
(c) i(t) = 20(a)
cos(10t
+ 3π/6)
µA,
q(0)
= 2 µCat:
i(t)Fig.
=
A, q(0)
1 Ccurrent
10 i (A)
−30t (a) t = 1 ms
(b)
(c) t = 10 ms
(d) i(t) = 10e
sin
40t
A,
q(0)
=
0
(b) i(t) = (2t + 5) mA, q(0)t =
= 60 ms
0
2 t (ms)
1 10
(c) i(t)through
= 20 cos(10t
+ is
π/6) µA, q(0) = 2 µC
The current flowing
a device
(d) A.
i(t)Calculate
= 10e−30t
40tcharge
A, q(0)
=0
i(t) = 5 sin 6πt
thesin
total
flow
Figure 1.22 For Prob.
1.8.
5
0
2 t (ms)
1
through the device from t = 0 to t = 10 ms.
1.4
The current
flowing
through
a
device
is
q(t) (mC)
an element
is shown
= charge
5 sin 6πt
A. Calculate
the total charge1.9
flow The current through
Determine thei(t)
total
flowing
into an element
Figure 1.22
For Prob.
1.8. in Fig.
4
5 t (s)
1.23. Determine the total0charge1 that 2passed3through
80 from
t = its
0 to t = 10 ms.
for 0 < t < 2through
s when the device
current
entering
the element at:
positive terminal is i(t) = e−2t mA.
The current
throughFor
an Prob.
element
is shown in Fig.
1.5
Determine the total charge flowing into an element (a) t 1.9
Figure
= 1 s 1.23.(b)Determine
t = 31.23
s the total
(c) tcharge
=1.9.
5 s that passed through
for 0 <at certain
< 2 s when
theiscurrent
its
The charge entering
element
shownentering
in
the element
positive
terminal
Fig. 1.20. Find
the current
at: is i(t) = e−2t mA.
Sections
1.4at:
and 1.5
Voltage, Power, and
i (A)
(a) t = 1 s
(b) t = 3 sEnergy
(c) t = 5 s
(a) t 1.6
= 1 ms The (b)
t
=
6
ms
(c)
t
=
10
ms
charge entering a certain element is shown in
10
Fig. 1.20. Find the current at:
1.10
A certain electrical element draws the current
i (A)
(a) t = 1 ms
(b) t = 6 ms
(c) t = 10 ms
i(t) = 10 cos 4t A at a voltage v(t) = 120 cos 4t V.
5
10 Find the energy absorbed by the element in 2 s.
0
2
4
6
8 10 12 t (ms)
▲
1.2
▲
▲
1.2
The voltage v across a device and the current i
through it are
e-Text Main Menu| Textbook Table of Contents |Problem Solving Workbook Contents
v(t)
= 5 cos
2t voltage
V,
= 10(1
− e−0.5t
A current i
1.11
The
vi(t)
across
a device
and) the
6A
12 V
+
!
1A
3A
0
1
3
4 t (s)
24
Figure 1.24
30 V
PART 1
DC Circuits
For Prob. 1.13.
+
Vo
!
+
!
+
!
28 V
–
+
6A
5Io
3A
The current
entering the positive terminal of a
1.16
Determine Io in the circuit of Fig. 1.27.
Section 1.6 1.12 Circuit
Elements
device is i(t) = 3e−2t A and the voltage across the
Figure 1.28 For Prob. 1.17.
1.14
Figure 1.25 shows
five elements.
If
devicea iscircuit
v(t) =with
5 di/dt
V.
12 V
p1 = −205 W,
p
=
60
W,
p
=
45
W,
p
=
30
W,
+
!
4 delivered 5to the device between
(a) 2Find the charge
calculate the power
received
t =p03 and
t = 2or
s. delivered by
Section 1.7
Applications
Io
5A
element 3.
(b) Calculate the power absorbed.
+
1.18
It takes eight photons
to strike the surface of a +
+
(c) Determine
20
V
2
4 the energy absorbed in 3 s.
20 Vone electron. If 8 V
!
photodetector in order to emit
1.13
Figure 1.24 shows the current through and the
4 × 1011 photons/second strike! the surface of the!
voltage
across a device.
Find the total energy
photodetector, calculate the amount of current flow.
1
3
5
absorbed by the device for the period of 0 < t < 4 s.
1.19
Find the power rating of the following electrical3 A
i (mA)
appliances in your household:
50
Figure 1.27 For (b)
Prob.Radio
1.16. set
(a) Lightbulb
Figure 1.25 For Prob. 1.14.
(c) TV set
(d) Refrigerator
Find
Vo in the circuit
of Fig.
1.28.
(e)1.17
Personal
computer
(f ) PC
printer
1.15
Find the power absorbed by each of the elements in
(g) Microwave oven
(h) Blender
Fig. 1.26.
0
I = 10 A
30 V
+
!
2
10 V
+ v!(V)
10
p2
+
14 A
+
20 V
0!
p1
Figure 1.24
8V
!
4 t (s)
4A
1.20
p4
p5
+
12 V
3
4 !t (s) 0.4I
p3
1
For Prob. 1.13.
▲
|
▲
|
!
Vo
A 1.2-kW toaster takes roughly 4!minutes to heat
–
+
four slices of
6 Abread. Find the cost of operating the
toaster once per day for 1 month (30 days). Assume
energy costs 9 cents/kWh.
1.6Prob. 1.15.
Circuit Elements
FigureSection
1.26 For
1.14
Io = 2 A
A 1.5-kW electric heater is connected to a 120-V
source.
+
!
28 V
(a) How much current does
the heater draw?
12
V
1
A
6A
!
(b) If the heater is on for+ 45 minutes,
how much
energy is consumed in kilowatt-hours (kWh)?
+
!
3A
28 for
V 45
(c) Calculate the cost of operating the heater
+
minutes if energy
costs 10 cents/kWh.
+
30 V
1.21
3A
Figure 1.28
Figure 1.25 shows a circuit with five elements. If
p1 = −205 W, p2 = 60 W, p4 = 45 W, p5 = 30 W,
calculate the power p3 received or delivered by
element 3.
5Io
3A
For Prob. 1.17.
Workbook Contents
e-Text Main Menu| Textbook Table of ContentsSection
|Problem
1.7 Solving
Applications
2
1
Figure 1.25
1.15
4
3
1.18
It takes eight photons to strike the surface of a
photodetector in order to emit one electron. If
4 × 1011 photons/second strike the surface of the
photodetector, calculate the amount of current flow.
1.19
Find the power rating of the following electrical
appliances in your household:
(a) Lightbulb
(b) Radio set
(c) TV set
(d) Refrigerator
(e) Personal computer (f ) PC printer
(g) Microwave oven
(h) Blender
5
For Prob. 1.14.
Find the power absorbed by each of the elements in
Fig. 1.26.