some basics electrical and electronics knowledge

This chapter discribe about common electrical divices such as passive component, the internaltional system unit and international system prefixes.

1. CHATER 1. SOME BASIC
ELECTRICAL AND ELECTRONIC
KNOWLEDGE
Nguyen Thi Thu
Wednesday, October 12, 2022

2. CIRCUIRT ELEMENTS
ACTIVE ELEMENTS
VOLTAGE SOURCES,
CURRENT SOURCES
AMPLIFIRES
PASIVE ELEMENTS
RESISTOR
CAPACITOR
INDUCTOR
1.1. Basic physical quantities,
system of Units, symbols and graphs

3. current
charge
voltage
resistance
power
ampere A
coulomb C
volt V
ohm 
watt W
Page 3
Quantity Unit Symbol
1.1. Basic physical quantities,
system of Units, symbols and graphs

4. length
mass
time
electric current
temperature
luminous intensity
amount of substance
meter m
kilogram kg
second s
ampere A
Kelvin K
candela cd
mole mol
Quantity Unit Symbol
Page 4
1.1. Basic physical quantities,
system of Units, symbols and graphs

5. 47,000,000 = 4.7 x 10
7 (Scientific Notation)
= 47. x 10
6 (Engineering Notation)
0.000 027 = 2.7 x 10
-5 (Scientific Notation)
= 27 x 10
-6 (Engineering Notation)
1.1. Basic physical quantities,
system of Units, symbols and graphs
Page 5

6. P
T
G
M
k
peta
tera
giga
mega
kilo
10
15
10
12
10
9
10
6
10
3
Can you name
the prefixes and
their meaning?
Page 6
1.1. Basic physical quantities,
system of Units, symbols and graphs

7. 10
-3
10
-6
10
-9
10
-12
10
-15
milli
micro
nano
pico
femto
m

n
p
f
Can you name
the prefixes and
their meaning?
Page 7
1.1. Basic physical quantities,
system of Units, symbols and graphs

8. 0.47 M = 470 k
Larger number
Larger unit
1.1. Basic physical quantities,
system of Units, symbols and graphs
Smaller unit
10,000 pF = 0.01 F
Smaller number
Page 8

9. Quiz
2.The electrical unit that is fundamental is the
a.volt
b.ohm
c.coulomb
d.ampere
Page 9
1.1. Basic physical quantities,
system of Units, symbols and graphs

10. 3.The metric prefix nano means
a.10
-3
b.10
-6
c.10
-9
d.10
-12
Page 10
1.1. Basic physical quantities,
system of Units, symbols and graphs

11. 4.The metric prefix pico means
a.10
-3
b.10
-6
c.10
-9
d.10
-12
Page 11
1.1. Basic physical quantities,
system of Units, symbols and graphs

12. 5.The number 2700 MW can be written
a.2.7 TW
b.2.7 GW
c.2.7 kW
d.2.7 mW
Page 12
1.1. Basic physical quantities,
system of Units, symbols and graphs

13. 6.The value 68 kW is equal to
a.6.8 x 10
4 W
b.68, 000 W
c.0.068 MW
d.All of the above
Page 13
1.1. Basic physical quantities,
system of Units, symbols and graphs

14. Sources
1.1. Basic physical quantities,
system of Units, symbols and graphs

15. Ideal Energy Sources
An ideal voltage source provides constant voltage independent of the
current through it
An ideal current source provides constant current
voltage across it
independent of the
Ideal sources do not exist in reality, due to such dilemmas:
•When (short circuit) is the load of a voltage source
where is the current through .
•When (open circuit) is the load of a current source
where is the voltage across .
, the load voltage is
, the load current is ,
1.1. Basic physical quantities, system
of Units, symbols and graphs

16. Voltage Source
1.1. Basic physical quantities,
system of Units, symbols and graphs

17. Current Source
1.1. Basic physical quantities,
system of Units, symbols and graphs

18. Electronic components are the basic building blocks of an
electronic circuit. Electronic components are very small, cheep and have
two or more terminals. When a group of electronic components is
connected together in an printed circuit board (PCB), a useful electronic
circuit is formed. Electronic components are classified as ……
Page 18
1.2. Passive Circuit elements

19. RESISTOR
(which gives resistance in any
electrical circuit or network)
American-style symbols. (a) resistor,
(b)rheostat (variable resistor), and
(c)potentiometer
style resistor symbol
1.2. Passive Circuit elements

20. Showing a resistor(axial lead resistor)
component with 330 Ω and a
tolerance of 5%
An aluminium-housed power resistor
rated for 50 W when heat-sinked
A single in line (SIL) resistor package
with 8 individual, 47 ohm resistors. One
end of each resistor is connected to a
separate pin and the other ends are all
connected together to the remaining
(common) pin – pin 1, at the end
identified by the white dot.
Partially exposed Tesla TR-212 1 kΩ
carbon film resistor
Three carbon composition resistors
in a 1960s valve (vacuum tube) radio
Resistors with wire leads for
through-hole mounting
1.2. Passive Circuit elements

21. Different types of capacitors: From left: multilayer ceramic, ceramic disc, multilayer
polyester film, tubular ceramic, polystyrene, metalized polyester film, aluminum
electrolytic. Major scale divisions are in centimeters.
(a passive two-terminal electrical component used to store energy electrostatically in an electric field. It is
characterized by capacitance)
1.2. Passive Circuit elements
CAPACITOR

22. Types of Capacitors
Parallel-Plate Capacitor Cylindrical Capacitor
A cylindrical capacitor is a parallel-plate capacitor that has
been rolled up with an insulating layer between the plates.
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1.2. Passive Circuit elements

23. Charge Q stored:
Q = CV
Page 23
The stored charge Q is proportional to the
potential difference V between the plates. The
capacitance C is the constant of proportionality,
measured in Farads.
Farad = Coulomb / Volt
1.2. Passive Circuit elements
Capacitors and Capacitance
A capacitor in a simple electric
circuit.

24. 1.2. Passive Circuit elements
Page 24

25. FIXED CAPACITORS
▪Capacitor whose capacitance value is fixed.
1.2. Passive Circuit elements
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26. Electrolytic capacitors
• A Electrolytic capacitors are a type
of capacitor that is polarized.
•Made of aluminum plates & oxide
as dielectric
• They are able to offer high
capacitance values - typically above
1μF
•Low frequency applications - power
supplies, decoupling and
coupling applications as they
audio
have
a frequency limit if around 100 kHz.
1.2. Passive Circuit elements
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27. Mica capacitors
•Not polarized.
• Made of metal plates & mica as
the dielectric.
•Range – 5 to 10000 Pf
applications –
and high
•Rated upto 500 v
• High frequency
resonance circuits
frequency filters.
1.2. Passive Circuit elements
Page 27

28. Ceramic capacitors
•Not polarized.
• Made of silver/copper plates &
titanium/barium as the dielectric.
•Range – 3pf to 2µf
•High frequency applications
1.2. Passive Circuit elements
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29. Paper capacitors
•Not polarized.
• Made of aluminum foils separated
by strips of paper soaked in
dielectric (wax, plastic or oil).
•Range – 0.0005 µf to several µf
•Disadvantage – large size
•High voltage applications
1.2. Passive Circuit elements
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30. VARIABLE CAPACITORS
▪Capacitor whose capacitance value can be varied
1.2. Passive Circuit elements
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31. sGang capacitor
•Rotor – stator arrangement with two sets of metal plates
•Fixed plates – Stator, Movable plates – Rotor
•Movable plate connected to the shaft & capacitance is
varied by rotating the shaft.
•Applications – tuning of radio receivers.
1.2. Passive Circuit elements
Page 31

32. Trimmer
•Construction – metal plates separated by dielectric (mica/ceramic )
•Capacitance variation is done by rotating the screw.
•Range – in pf
• Applications – used where tuning is not very frequent (tuning of
broadcast receivers).
1.2. Passive Circuit elements
Page 32

33. Padder
•Construction – aluminium plates separated by dielectric (air)
•Capacitance variation is done by rotating the screw.
•Range – 5pF to 600pF
1.2. Passive Circuit elements
Page 33

34. NUMBERING OF CAPACITORS
Number > 1 = PF
Number < 1 = µF
104 means
10,0000pF
1.2. Passive Circuit elements
Page 34

35. NUMBERING OF CAPACITORS
10k means 10kpF
47n means 47nF
47M means 47MF
4k7 means 4.7kpF
2M2 means 2.2MpF
Page 35
104k means 10% & 104M
means 20% tolerance
1.2. Passive Circuit elements

36. Ferrite rod antenna loopstick (bottom) and RF chokes, coils and IF transformers (top) used in radio equipment. The ferrite antenna has two
windings, to receive both the LW and MW bands. The loopstick and chokes at top right are wound with litz wire in a basket weave pattern,
with adjacent winding layers at different angles, to reduce resistance due to proximity effect and skin effect.
A selection of low-value inductors
Axial lead inductors (100 µH)
A ferrite "bead" choke, consisting of
an encircling ferrite cylinder, removes
electronic noise from a computer
power cord.
INDUCTOR
(a passive two-terminal electrical component which resists changes in electric current passing through it. When a
current flows through it, energy is stored temporarily in a magnetic field in the coil. )
1.2. Passive Circuit elements

37. INDUCTOR
1.2. Passive Circuit elements
Page 37

38. •Values specified in henries (H), millihenries (mH) and
microhenries (μH)
• Inductance is the property of inductors by which it opposes
any change in the flow of current.
• A coil of wire that may be wound on a core of air or other
non-magnetic material, or on a magnetic core such as iron
powder or ferrite.
•Two coils magnetically coupled form a transformer.
1.2. Passive Circuit elements
Page 38

39. Ferrite core
Iron core inductor
Air core inductor
TYPES OF INDUCTOR
Page 39
1.2. Passive Circuit elements

40. TRANSFORMER
1.2. Passive Circuit elements
Page 40

41. WHAT IS TRANSFORMER
■A transformer is a static piece of apparatus by means
of which an electrical power is transferred from one
alternating current circuit to another electrical
circuit
■There is no electrical contact between them
■The desire change in voltage or current without any
change in frequency
IT WORKS ON THE PRINCIPLE OF MUTUAL
INDUCTION
Page 41
1.2. Passive Circuit elements

42. STEP-DOWN TRANSFORMER
A step-down transformer is one who’s secondary windings are fewer
than the primary windings. In other words, the transformer’s
secondary voltage is less than the primary voltage. So, the
transformer is designed to convert high-voltage, low-current power
into a low-voltage, high current power and it is mainly used in
domestic consumption.
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1.2. Passive Circuit elements

43. STEP-UP TRANSFORMER
A step-up transformer is the direct opposite of a step-down transformer.
There are many turns on the secondary winding than in the primary winding
in the step-up transformers. Thus, the voltage supplied in the secondary
transformer is greater than the one supplied across the primary winding.
Because of the principle of conservation of energy, the transformer converts
low voltage, high-current to high voltage-low current. In other words, the
voltage has been stepped up.
Page 43
1.2. Passive Circuit elements

44. INTERMEDIATE FREQUENCY TRANSFORMER
IntermediateFrequency (IF) Transformers work at frequency of
Page 44
455kHz and cased with aluminium can. Tuning is achieved by using
parallel capacitors across primary and secondary windings.
Application – Radio recievers
1.2. Passive Circuit elements

45. High power source
Low power source
Relay
Load
RELAY
1.2. Passive Circuit elements
Page 45

46. When a relay is used to switch a large amount of electrical power
through its contacts, it is designated by a special name: contactor.
CONTACTORS
Page 46
1.2. Passive Circuit elements

47. INTRODUCTION KIRCHOFF’S LAW
KIRCHOFF’S VOLTAGE LAW ( KVL )
ANALYSIS CIRCUIT OF KVL
KIRCHOFF’S CURRENT LAW ( KCL )
ANALYSIS CIRCUIT OF KCL
QUIZ
1.3. Kirchhoff's Law

48. HISTORY OF KIRCHOFF’S LAW
INTRODUCTION
TYPES OF KIRCHOFF’S LAW
1.3. Kirchhoff's Law

49. described two laws that became
central to electrical engineering in
1845
The laws were generalized from the
work of Georg Ohm
It’s can also be derived from
Maxwell’s equations, but were
developed prior to Maxwell’s work
Gustav Robert
Kirchhoff
(German physicist)
1.3. Kirchhoff's Law

50. KVL
• Kirchoff Voltage
Law
KCL
• Kirchoff Current
Law
1.3. Kirchhoff's Law

51. INTRODUCTION KVL
MESH ANALYSIS
EXERCISE
1.3. Kirchhoff's Law

52. Kirchhoff's Voltage Law - KVL - is one of two fundamental laws in
electrical engineering, the other being Kirchhoff's Current Law (KCL)
KVL is a fundamental law, as fundamental as Conservation of Energy
in mechanics, for example, because KVL is really conservation of
electrical energy
KVL and KCL are the starting point for analysis of any circuit
KCL and KVL always hold and are usually the most useful piece of
information you will have about a circuit after the circuit itself
1.3. Kirchhoff's Law

53. Kirchoff’s Voltage Law (KVL) states that the
algebraic sum of the voltages across any set
of branches in a closed loop is zero. i.e.;
 Vacrossbranches = 0
1.3. Kirchhoff's Law

54. 1.3. Kirchhoff's Law
Below is a single loop circuit. The KVL computation is expressed
graphically in that voltages around a loop are summed up by
traversing (figuratively walking around) the loop.
+
-
+ Vr1 -
+ Vr2 -
+ Vr3 -
10V
R1
R3
Part of Traversal
Resulting KVL Equation: Vr1+Vr2+Vr3-10=0
Assumed
current R2
direction

55. The KVL equation is obtained by traversing a circuit loop in either direction
and writing down unchanged the voltage of each element whose “+” terminal
is entered first and writing down the negative of every element’s voltage
where the minus sign is first met.
The loop must start and end at the same point. It does not matter where you
start on the loop.
Note that a current direction must have been assumed. The assumed current
creates a voltage across each resistor and fixes the position of the “+” and “-”
signs so that the passive sign con-vention is obeyed.
The assumed current direction and polarity of the voltage across each resistor
must be in agreement with the passive sign convention for KVL analysis to
work.
The voltages in the loop may be summed in either direction. It makes no
difference except to change all the signs in the resulting equation.
Mathematically speaking, its as if the KVL equation is multiplied by -1. See
the illustration below.
1.3. Kirchhoff's Law

56. +
-
+ Vr1 -
+ Vr2 -
+ Vr3 -
10V
R1
R2
R3
Part of Traversal
Resulting KVL Equation: Vr1+Vr2+Vr3-10=0
+
-
+ Vr1 -
+ Vr2 -
+ Vr3 -
10V
R1
R2
R3
Part of Traversal
Resulting KVL Equation: -Vr1-Vr2-Vr3+10=0
For both summations, the assumed current direction was the same
Summation of voltage terms may be done in either direction
1.3. Kirchhoff's Law

57. For both cases shown, the direction of summation was the same
Assuming the current direction fixes the voltage references
+
-
+ Vr1 -
+ Vr2 -
+ Vr3 -
10V R2
Resulting KVL Equation: Vr1+Vr2+Vr3-10=0
R1
Assumed
current
direction
R3
+
+ Vr1 -
+ Vr2 -
+ Vr3 -
10V R2
Resulting KVL Equation: -Vr1-Vr2-Vr3-10=0
R1
Assumed
current
- direction
R3
1.3. Kirchhoff's Law

58. ❖Analysis using KVL to solve for the currents around each closed loop of
the network and hence determine the currents through and voltages
across each elements of the network
❖Mesh analysis procedure
STEP 1
Assign a distinct current to
each closed loop of the
network
STEP 2
Apply KVL around each
closed loop of the network
STEP 3
Solve the resulting
simultaneous linear equation
for the loop currents
1.3. Kirchhoff's Law

59. ❖Exercise 1
Find the current flow through each resistor using mesh analysis for
the circuit below
1.3. Kirchhoff's Law

60. ❖EXERCISE 1
❖SOLUTION
•Assign a
distinct
current to
each closed
loop of the
network
STEP 1
STEP 2
•Apply KVL
around each
closed loop of
the network
•Solve the
resulting
simultaneous
linear equation
for the loop
currents
STEP 3
1.3. Kirchhoff's Law

61. S
T
E
P
1.3. Kirchhoff's Law
1

62. Loop1:
I1 R 1 + I1 R 3 + I 2 R3 = V1
10 I1 + 40 I1 + 40 I 2 = 10
50 I1 + 40 I 2 = 10 − − − − equation1
Loop 2 :
I 2 R2 + I 2 R 3 + I1 R3 = V2
20I2 + 40I2 + 40I1 = 20
40 I1 + 60 I 2 = 20 − − − −equation 2
T
2
E
P
1.3. Kirchhoff's Law
S

63. 40 20
10
= 1000 − 400 = 600
=
50
20 60
40 60
40
= 3000 −1600 = 1400
 =
50

20

40I 1 
=
10

4060

I

2
FromKCL :
I3 = I1 + I2 = −0.143A + 0.429 A = 0.286 A
 1400
I =
I
2
=
600
= 0.429 A
 1400
1I =
I
1
=
− 200
= −0.143A
2
I
1
40
= 600 − 800 = −200I =
10
  2   
50I1 + 40I2 = 10
40I1 + 60I2 = 20
Matrixform :
50
Solve equation 1 and equation 2 using Matrix
S
E
T
P
3
1.3. Kirchhoff's Law

64. INTRODUCTION KCL
NODES ANALYSIS
EXERCISE
1.3. Kirchhoff's Law

65. Kirchhoff ’s Current
Law is sometimes
called “Kirchhoff’s
First Law” or
“Kirchhoff ’s Junction
Rule”
along with Kirchhoff’s
Voltage Law makes up
the two fundamental
laws of Electrical
Engineering
1 In this lesson it will be
shown how Kirchhoff’s
Current Law describes
the current flow
through a junction of
a circuit
2
1.3. Kirchhoff's Law

66. KCL helps to
solve unknowns
when working
with electrical
circuits
3
KCL with the
addition of KVL
and Ohm’s Law
will allow for
the solution of
complex circuits
4

67. Examples of a Junction
1.3. Kirchhoff's Law
•Definition that will help in understanding
Kirchhoff’s Current Law:

68. •Kirchhoff’s Current Law generally states:
•Restated as:
1.3. Kirchhoff's Law

69. •The algebraic sum of all currents entering (+) and leaving (-)
any point (junction) in a circuit must equal zero.
•Here, the 3 currents entering the node, I1, I2, I3 are all
positive in value and the 2 currents leaving the node, I4 and
I5 are negative in value. Then this means we can also
rewrite the equation as;
??????1 + ??????2 + ??????3 − ??????4 − ??????5 = 0
1.3. Kirchhoff's Law

70. Analysis using KCL to solve for
voltages at each common node
of the network and hence
determine the currents though
and voltages across each
elements of the network.
1.3. Kirchhoff's Law

71. •Determine the number of
common nodes and
reference node within the
network
Common
node
•Assign current and its
direction to each distinct
branch of the nodes in
the network
Current
Direction
•Apply KCL at each
of the common
nodes in the network
KCL
•Solve the resulting
simultaneous linear
equation for the node
voltage
Solve
Equation
Determine
I and V
•Determine the currents
through and voltages
across each elements
in the network
1.3. Kirchhoff's Law

72. Example 1:
Find the current flow through each resistor using node analysis for
the circuit below.
1.3. Kirchhoff's Law

73. Determine the number
of common nodes and
reference node within
the network.
1 common node (Va)
and 1 reference node C
Assign current and
its direction to each
distinct branch of the
nodes in the network
(refer o the figure)
Apply KCL at
each of the
common nodes in
the network
KCL: I1 + I2 = I3
REMEMBER THE STEPS EARLIER??
EXERCISE
1.3. Kirchhoff's Law

74. 40
Va = 11.428V
Va (
1
+
1
+
1
) = 2
40 10 20
Va (
7
) = 2
1-
Va
+1-
Va
=
Va
10 20 40
Va
+
Va
+
Va
= 2
40 10 20
20
I3 =
11.428
= 0.286V
40
10
I2 =
(20-11.428)
= 0.429A
I1 =
(10 -11.428)
= - 0.143A
DET1013 : ELECTRICAL TECHNOLOGY
1.3. Kirchhoff's Law

75. Example 2:
Find the current flow through each resistor using node analysis for
the circuit below.
1.3. Kirchhoff's Law

76. Determine the number
of common nodes and
reference node within
the network.
1 common node (Va)
and 1 reference node C
Assign current and
its direction to each
distinct branch of the
nodes in the network
(refer o the figure)
Apply KCL at
each of the
common nodes in
the network
KCL: I1 = I2 + I3
REMEMBER THE STEPS EARLIER??
1.3. Kirchhoff's Law

77. 5k 3k 6k 3k 5k
- Va (
1
+
1
+
1
=
55
-
40
5k 3k 6k 3k 5k
- Va (700 x10
-6
) =10.33x10
-3
Va = -14.757V
(40- Va)
=
(Va - (-55))
+
Va
5k 3k 6k
40
-
Va
=
Va
+
55
+
Va
6k 6k 3k 3k 6k
(-Va)
-
Va
-
Va
=
55
-
40
= - 2.46mA
6k
3k
(-14.757)
I3 =
=13.41mA
5k
(-14.757+55)
I1 =
I2 =
=10.95mA
(40-(-14.757))
1.3. Kirchhoff's Law

78. Q1 Q2 Q3 Q4 Q5
Q6 Q7 Q8 Q9 Q10
1.3. Kirchhoff's Law

79. Kirchhoff’s First
Law says that:
Current loses strength as it flows about a circuit
Voltage loses strength as it flows about a circuit
Wires need insulation to stop electrons from leaking out
of the wire
Total current flowing into a point is the same as
the current flowing out of that point
1.3. Kirchhoff's Law

80. KCL is used when solving circuits with…
Closed loops
Sufficient nodes/ junctions
Capacitors
None
1.3. Kirchhoff's Law

81. Nodal Analysis applies the following principles…
KVL & Ohm’s Law
KCL & Ohm’s Law
KVL & Superposition
KCL & Superposition
1.3. Kirchhoff's Law

82. Which of the following statements is true?
Mesh Analysis employs KVL to solve loop currents
All of t All of the above
Mesh Analysis is easiest when a circuit has more than two nodes
Mesh Analysis is more difficult than Nodal Analysis
1.3. Kirchhoff's Law

83. 1.3. Kirchhoff's Law
If a circuit contains three loops, how many
independent equations can be obtained with
Kirchhoff’s Second laws?
Three
Four
Five
Six

84. How much is current I3 in the node shown?
2A
-2A
0A
8A
1.3. Kirchhoff's Law

85. How much is current I4 in the node shown?
2A
-2A
18A
8A
1.3. Kirchhoff's Law

86. How much is voltage V3 in the closed loop circuit
shown?
2A
-2A
10A
-10A
1.3. Kirchhoff's Law

87. How much is voltage V4 in the closed loop circuit
shown?
4A
-4A
8A
-8A
1.3. Kirchhoff's Law

88. Using KVL, find the value of Rx in the circuit
shown
8Ω
4Ω
2Ω
1Ω
1.3. Kirchhoff's Law

89. -Electric field is defined as the electric force per
unit charge. The direction of the field is taken to
be the direction of the force it would exert on a
positive test charge. The electric field is radially
outward from a positive charge and radially in
toward a negative point charge.
1.4. Electric field, magnetic field and
electromagnetic field

90. E=F/q
Where;
E-Electric charge
F-Force (N)
q-Charge (C)
Electric Field
1.4. Electric field, magnetic field and
electromagnetic field

91. 1.4. Electric field, magnetic field and
electromagnetic field

92. 1.4. Electric field, magnetic field and
electromagnetic field
1.How much charge experiences a force of 5.0 x 10
-3N due
to an electric field of 10 N/C.
2. Two balloons are
charged with an identical quantity and type of
charge: -6.25 nC. They are held apart at a
separation distance of 61.7 cm. Determine the
magnitude of the electrical force of repulsion between
them.
3. Two balloons with
charges of +3.37 µC and -8.21 µC attract each other with a
force of 0.0626 N. Determine the
separation distance between the two balloons.

93. Magnetic Field
• -Magnetic fields are produced by electric
currents, which can be macroscopic currents in
wires, or microscopic currents associated with
electrons in atomic orbits.
1.4. Electric field, magnetic field and
electromagnetic field

94. Magnetic Interactions
-similar poles repel while opposite pole attracts.
1.4. Electric field, magnetic field and
electromagnetic field

95. Electric motors involve rotating coils of wire which are
driven by the magnetic force exerted by a magnetic field on
an electric current. They transform electrical energy into
mechanical energy.
1.4. Electric field, magnetic field and
electromagnetic field

96. Electric Motor
1.4. Electric field, magnetic field and
electromagnetic field

97. Electric Motor
1.4. Electric field, magnetic field and
electromagnetic field

98. Thank you, Q&A