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Essentials of Electrical and Computer Engineering

David V. Kerns, Jr., J. David Irwin

Chapter 1

Introduction - all with Video Answers

Educators


Chapter Questions

01:57

Problem 1

What is the charge, $q_1$, on an object that is attracted by a force of $3 \times 10^{-3}$ newtons, to a second charged object with a charge of $q_2=$ $+1.6 \times 10^{-6} \mathrm{C}$, and separated by one millimeter?

Hunza Gilgit
Hunza Gilgit
Numerade Educator
01:56

Problem 2

A micromachined insulating cantilever beam has a charge at the tip of the beam of $6.5 \mathrm{pC}$. The substrate located 4 microns $(1$ micron $=$ $1 \mu=1 \times 10^{-6}$ meter) under the beam has a mirror charge of $-6.5 \mathrm{pC}$. What is the magnitude of the force pulling down on the tip of the beam?

Vishal Gupta
Vishal Gupta
Numerade Educator
02:36

Problem 3

Two identical point charges each of magnitude $0.03 \mu C$ separated by a distance of $1 \mathrm{~cm}$ experience what magnitude of force between them? Is this force attractive or repulsive?

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
01:11

Problem 4

Assume the radius of a hydrogen atom is $5.3 \times 10^{-9} \mathrm{~cm}$. Calculate the force between the nucleus of the hydrogen atom and an electron at this radius.

Prabhu Ramji
Prabhu Ramji
Numerade Educator
06:55

Problem 5

Three charges are placed in a straight line as shown in Figure P1.5.
FIGURE P1.5 can't copy
(a) If $q_1=-2 \mathrm{mC}, q_2=4 \mathrm{mC}$, and $q_3=10 \mathrm{mC}$, find the magnitude and direction of the resultant force on $q_1, q_2$, and $q_3$.
(b) If $q_1=-3 \mathrm{mC}$, find the magnitude and sign of the charge $q_3$ such that the resultant force on $q_2$ is zero.

Jacob Schulze
Jacob Schulze
Numerade Educator
00:35

Problem 6

Classify the following as insulators or conductors: iron, glass, rubber, gold, salt water, silver, ceramics, plastic, brass, wood, copper.

Kayla Gephart
Kayla Gephart
Numerade Educator
02:03

Problem 7

For each of the following pairs, identify which is the better electrical conductor: (a) wet aluminum or wet wood, (b) salt water or pure water, (c) copper or iron.

Mahipal Kumawat
Mahipal Kumawat
Numerade Educator
00:31

Problem 8

An electric heater operated from a dc source has $8.2 \times 10^{21}$ electrons pass through it in 10 seconds. How much current (in amperes) is flowing through the heater?

Mayukh Banik
Mayukh Banik
Numerade Educator
02:00

Problem 9

If an automobile battery delivers $120 \mathrm{~A}$ when the car is being started, and the starting process takes 6 seconds, how many electrons flow out of the battery?

Shahab Ullah
Shahab Ullah
Numerade Educator
01:23

Problem 10

If $3 \times 10^{19}$ electrons flow uniformly through the cross-section of a wire in $5 \mathrm{~s}$, what is the current flowing through the wire?

Nishant Kumar
Nishant Kumar
Numerade Educator
03:42

Problem 11

Three wires join at a common point or node. The first wire is conducting $3 \mathrm{~A}$ into the node and the second wire is conducting $1 \mathrm{~A}$ away from the node. What is the magnitude of the current in the third wire, and its direction?

Luis Rios
Luis Rios
Numerade Educator
01:06

Problem 12

Two identical automobile headlamps are connected across a $12 \mathrm{~V}$ battery. If the total current from the battery is measured to be $6.5 \mathrm{~A}$, what is the current through each headlamp?

Thomas Thompson
Thomas Thompson
Numerade Educator
01:40

Problem 13

How many electrons are flowing through the cross-section of a wire per second if a current of 0.2 A flows through it?

Vishal Gupta
Vishal Gupta
Numerade Educator
03:47

Problem 14

What is the typical current range for the following:
(a) Large industrial motor
(b) Household appliances
(c) Lightning bolt
(d) Memory cell of an integrated circuit memory

Yaqub Khan
Yaqub Khan
Numerade Educator
00:44

Problem 15

If a battery supplies 3 joule of energy in transferring 0.25 coulombs of charge through an element, what is the voltage across the battery?

Kara Merfeld
Kara Merfeld
Numerade Educator
00:55

Problem 16

A $12 \mathrm{~V}$ lantern battery provides $0.5 \mathrm{~A}$ to operate an electric bulb. During the time of operation of one-half hour,
(a) How many electrons pass through the bulb?
(b) What is the amount of power delivered to the bulb?
(c) How much energy is provided by the battery?

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
01:56

Problem 17

A CRT (cathode ray tube) is used for most television and computer video displays. In the back of a CRT is an electron gun emitting a beam of electrons toward a phosphor-coated display screen; the beam makes a visible spot where it impacts the screen. Assuming the electron gun is made $25 \mathrm{kV}$ more negative than the screen, how much energy is transferred to a single electron by the time it reaches the screen?

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
01:52

Problem 18

One electron-volt $(1 \mathrm{eV})$ is defined as the amount of energy gained by an electron moving through a voltage difference of 1 volt. What is this energy expressed in joules?

Matthew Baker
Matthew Baker
Numerade Educator
01:47

Problem 19

A $12 \mathrm{~V}$ car battery delivers $150 \mathrm{~A}$ of current during startup. If it takes one second to start the car, how much energy is supplied by the battery during ignition?

Vishal Gupta
Vishal Gupta
Numerade Educator
02:20

Problem 20

Categorize the following sources of electric power as either ac or dc.
1. automobile battery
2. solar cell
3. residential power outlet
4. watch battery
5. commercial power generating station
6. fuel cell

Vishal Gupta
Vishal Gupta
Numerade Educator
05:25

Problem 21

What is the approximate frequency (in $\mathrm{Hz}$ ) near the center of the portion of the electromagnetic spectrum corresponding to:
1. infrared
2. shortwave radio
3. gamma rays

Villiam Zelinsky
Villiam Zelinsky
Numerade Educator
02:36

Problem 22

What is the approximate frequency (in $\mathrm{Hz}$ ) near the center of the portion of the electromagnetic spectrum corresponding to (a) television, (b) ultraviolet light, (c) x-rays?

Narayan Hari
Narayan Hari
Numerade Educator
00:32

Problem 23

Assign values to $V$ and $I$ in element $B$ so that it is equivalent to element $A$ (see Figure P1.23).
Figure P1.23 can't copy

Ashley High
Ashley High
Numerade Educator
01:06

Problem 24

Assign directions to currents and polarities to voltages in element $B$ so it is equivalent to element $A$ (see Figure P1.24).
Figure P1.24 can't copy

Carson Merrill
Carson Merrill
Numerade Educator
02:18

Problem 25

In the elements of Figure P1.25, determine for each if they are supplying power or absorbing power and the magnitude of the power being transferred.
Figure P1.25 can't copy

WM
William Mead
Numerade Educator
02:18

Problem 26

In Figure P1.26 determine for each element whether it is supplying or absorbing power. If all the energy absorbed is dissipated as heat, determine the heat dissipated (in joules) over a period of one hour for each of the circuits shown.
Figure P1.26 can't copy

WM
William Mead
Numerade Educator

Problem 27

A dependent voltage source shown in Figure 1.15 (a) has $\mu=25$. (a) What is the voltage between the terminals on the right, if $v_i=4.3 \mathrm{~V}$ ? (b) If $v_i=30 \mathrm{~V}$ ?

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Problem 28

A current-dependent current source has $\beta=30$ and produces an output current of $2 \mathrm{~mA}$. What current is flowing through its input terminals?

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Problem 29

What voltage appears at the output of a voltage-dependent voltage source, if $\mu=10^3$ and the voltage applied to the input terminals is $3 \times 10^{-4} \mathrm{~V}$ ?

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05:40

Problem 30

In the circuit of Figure P1.30, if $\mu=48$, calculate the value of $V_o$.
Figure P1.30 can't copy

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
05:40

Problem 31

In the circuit of Figure P1.31, the output voltage, $V_o$, is measured to be 30 volts. Calculate the value of $\mu$.
Figure P1.31 can't copy

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator

Problem 32

In the circuit of Figure P1.32, plot the output voltage, $v_o(t)$, as a function of time. Carefully label the axes.
Figure P1.32 can't copy

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04:30

Problem 33

In the circuits of Figure P1.33, a voltage-dependent current source with $g=10^{-3}$ (assume units of volts divided by amperes, or siemens) produces what current through the resistor, $R$ ?
Figure P1.33 can't copy

Km Neeraj
Km Neeraj
Numerade Educator
04:30

Problem 34

In the circuits of Figure P1.34, a current-dependent current source with $\beta=25$ produces what current through the resistor, $R$ ?
Figure P1.34 can't copy

Km Neeraj
Km Neeraj
Numerade Educator