CAPACITORS
AND
INDUCTORS
FUNDAMENTALS OF ELECTRICAL AND ELECTRONICS
ENGINEERING
• Element that stores energy in an electric field.
CAPACITOR
Fig: Circuit Symbol Fig: Capacitor Model
TYPES OF CAPACITOR
• 𝜈 ∝ 𝑞
• 𝜈 =
𝑑
𝐴 𝜖
𝑞
• 𝐶 =
𝐴 𝜖
𝑑
• Hence, q=Cv
• Capacitor Equation: ⅈ =
ⅆ𝑞
ⅆ𝑡
= 𝐶
ⅆ𝜈
ⅆ𝑡
• Here,
v= Voltage
q= Quantity of charge
C= Capacitance
i= Current
∈= Permittivity
GENERAL EQUATIONS OF CAPACITOR
• ⅈ = 𝑖1 + 𝑖2 = 𝐶1
ⅆ𝑣
ⅆ𝑡
+ 𝐶2
ⅆ𝑣
ⅆ𝑡
• ⅈ = (𝐶1 + 𝐶2)
ⅆ𝑣
ⅆ𝑡
• Same as a single capacitor of value (𝐶1 + 𝐶2)
PARALLEL CAPACITORS
Fig: Parallel Combination
•
ⅆ𝜈
ⅆ𝑡
=
ⅆ 𝑣1+𝑣2
ⅆ𝑡
=
ⅆ𝜈1
ⅆ𝑡
+
ⅆ𝑣2
ⅆ𝑡
=
ⅈ
𝐶1
+
ⅈ
𝐶2
= ⅈ
1
𝐶1
+
1
𝐶2
= ⅈ
𝐶1+𝐶2
𝐶1 𝐶2
• ⅈ =
𝐶1 𝐶2
𝐶1+𝐶2
ⅆ𝜈
ⅆ𝑡
• Same as a single capacitor of value
𝐶1 𝐶2
𝐶1+𝐶2
SERIES CAPACITORS
Fig: Series Combination
NON IDEAL CAPACITOR
EXAMPLE
Figure 1 Figure 2
Energy stored in capacitors:
1. For capacitor 𝐶1: 0 Joules
2. For capacitor 𝐶2: 𝐸 𝐶2
=
1
2
𝐶2 𝑣2
=
1
2
1 × 10−6
× 102
= 50𝜇 Joules
3. For capacitor 𝐶3: 𝐸 𝐶3
=
1
2
𝐶3 𝑣2 =
1
2
10 × 10−6 × 102 = 500𝜇 Joules
EXAMPLE
SYNOPSIS
• Stores energy in an electric field.
• Current –voltage relationship: ⅈ = 𝐶
ⅆ𝜈
ⅆ𝑡
• Energy stored: 𝐸 =
1
2
𝐶𝑣2
• Unit: Farad
• Typical capacitor values are in mF to pF.
• In DC, acts as an open circuit.
• Coil which stores energy in the magnetic
field.
INDUCTORS
Fig: Inductor Model
Fig: Circuit Symbol
• According to the figure: 𝜙 =
𝜇𝑁𝐴
𝑙
ⅈ
Where, 𝜙= Magnetic flux
• From Farad’s Law:
𝜈 = 𝑁
ⅆ𝜙
ⅆ𝑡
=
𝜇𝑁2 𝐴
𝑙
⋅
ⅆⅈ
ⅆ𝑡
= 𝐿
ⅆⅈ
ⅆ𝑡
Where, L= Inductance
=
𝜇𝑁2 𝐴
𝑙
GENERAL EQUATIONS OF INDUCTOR
• 𝑣 = 𝜈1 + 𝜈2 = 𝐿1
ⅆⅈ
ⅆ𝑡
+ 𝐿2
ⅆⅈ
ⅆ𝑡
=(𝐿1+ 𝐿2)
ⅆⅈ
ⅆ𝑡
• Same as a single inductor of value: 𝐿1+ 𝐿2
PARALLEL INDUCTORS
Fig: Parallel Combination
•
ⅆ𝑖
ⅆ𝑡
=
ⅆ 𝑖1+𝑖2
ⅆ𝑡
=
ⅆ𝑖1
ⅆ𝑡
+
ⅆ𝑖2
ⅆ𝑡
=
v
𝐿1
+
v
𝐿2
= 𝑣
1
𝐿1
+
1
𝐿2
= 𝑣
𝐿1+𝐿2
𝐿1 𝐿2
• 𝑣 =
𝐿1 𝐿2
𝐿1+𝐿2
ⅆ𝑖
ⅆ𝑡
• Same as a single Inductor of value
𝐿1 𝐿2
𝐿1+𝐿2
SERIES INDUCTORS
Fig: Series Combination
NON IDEAL INDUCTOR
Q: Two coils connected in series have a self-inductance of 20mH and 60mH
respectively. The total inductance of the combination was found to be
100mH. Determine the amount of mutual inductance that exists between the
two coils assuming that they are aiding each other.
Ans: 𝐿 𝑇 = 𝐿1 + 𝐿2 ± 2𝑀
100= 20 + 60 + 2M
M= 10 mH
EXAMPLE
• Stores energy in a magnetic field.
• Current-voltage relationship: 𝜈 = 𝐿
ⅆⅈ
ⅆ𝑡
.
• Energy stored: 𝐸 =
1
2
𝐿𝑖2
.
• In DC, Behaves like a short circuit.
SYNOPSIS
THANK YOU
FOR STAYING WITH US THROUGH THE PRESENTATION

CAPACITORS AND INDUCTORS

  • 1.
  • 2.
    • Element thatstores energy in an electric field. CAPACITOR Fig: Circuit Symbol Fig: Capacitor Model
  • 3.
  • 4.
    • 𝜈 ∝𝑞 • 𝜈 = 𝑑 𝐴 𝜖 𝑞 • 𝐶 = 𝐴 𝜖 𝑑 • Hence, q=Cv • Capacitor Equation: ⅈ = ⅆ𝑞 ⅆ𝑡 = 𝐶 ⅆ𝜈 ⅆ𝑡 • Here, v= Voltage q= Quantity of charge C= Capacitance i= Current ∈= Permittivity GENERAL EQUATIONS OF CAPACITOR
  • 5.
    • ⅈ =𝑖1 + 𝑖2 = 𝐶1 ⅆ𝑣 ⅆ𝑡 + 𝐶2 ⅆ𝑣 ⅆ𝑡 • ⅈ = (𝐶1 + 𝐶2) ⅆ𝑣 ⅆ𝑡 • Same as a single capacitor of value (𝐶1 + 𝐶2) PARALLEL CAPACITORS Fig: Parallel Combination
  • 6.
    • ⅆ𝜈 ⅆ𝑡 = ⅆ 𝑣1+𝑣2 ⅆ𝑡 = ⅆ𝜈1 ⅆ𝑡 + ⅆ𝑣2 ⅆ𝑡 = ⅈ 𝐶1 + ⅈ 𝐶2 = ⅈ 1 𝐶1 + 1 𝐶2 =ⅈ 𝐶1+𝐶2 𝐶1 𝐶2 • ⅈ = 𝐶1 𝐶2 𝐶1+𝐶2 ⅆ𝜈 ⅆ𝑡 • Same as a single capacitor of value 𝐶1 𝐶2 𝐶1+𝐶2 SERIES CAPACITORS Fig: Series Combination
  • 7.
  • 8.
  • 9.
    Energy stored incapacitors: 1. For capacitor 𝐶1: 0 Joules 2. For capacitor 𝐶2: 𝐸 𝐶2 = 1 2 𝐶2 𝑣2 = 1 2 1 × 10−6 × 102 = 50𝜇 Joules 3. For capacitor 𝐶3: 𝐸 𝐶3 = 1 2 𝐶3 𝑣2 = 1 2 10 × 10−6 × 102 = 500𝜇 Joules EXAMPLE
  • 10.
    SYNOPSIS • Stores energyin an electric field. • Current –voltage relationship: ⅈ = 𝐶 ⅆ𝜈 ⅆ𝑡 • Energy stored: 𝐸 = 1 2 𝐶𝑣2 • Unit: Farad • Typical capacitor values are in mF to pF. • In DC, acts as an open circuit.
  • 11.
    • Coil whichstores energy in the magnetic field. INDUCTORS Fig: Inductor Model Fig: Circuit Symbol
  • 12.
    • According tothe figure: 𝜙 = 𝜇𝑁𝐴 𝑙 ⅈ Where, 𝜙= Magnetic flux • From Farad’s Law: 𝜈 = 𝑁 ⅆ𝜙 ⅆ𝑡 = 𝜇𝑁2 𝐴 𝑙 ⋅ ⅆⅈ ⅆ𝑡 = 𝐿 ⅆⅈ ⅆ𝑡 Where, L= Inductance = 𝜇𝑁2 𝐴 𝑙 GENERAL EQUATIONS OF INDUCTOR
  • 13.
    • 𝑣 =𝜈1 + 𝜈2 = 𝐿1 ⅆⅈ ⅆ𝑡 + 𝐿2 ⅆⅈ ⅆ𝑡 =(𝐿1+ 𝐿2) ⅆⅈ ⅆ𝑡 • Same as a single inductor of value: 𝐿1+ 𝐿2 PARALLEL INDUCTORS Fig: Parallel Combination
  • 14.
    • ⅆ𝑖 ⅆ𝑡 = ⅆ 𝑖1+𝑖2 ⅆ𝑡 = ⅆ𝑖1 ⅆ𝑡 + ⅆ𝑖2 ⅆ𝑡 = v 𝐿1 + v 𝐿2 = 𝑣 1 𝐿1 + 1 𝐿2 =𝑣 𝐿1+𝐿2 𝐿1 𝐿2 • 𝑣 = 𝐿1 𝐿2 𝐿1+𝐿2 ⅆ𝑖 ⅆ𝑡 • Same as a single Inductor of value 𝐿1 𝐿2 𝐿1+𝐿2 SERIES INDUCTORS Fig: Series Combination
  • 15.
  • 16.
    Q: Two coilsconnected in series have a self-inductance of 20mH and 60mH respectively. The total inductance of the combination was found to be 100mH. Determine the amount of mutual inductance that exists between the two coils assuming that they are aiding each other. Ans: 𝐿 𝑇 = 𝐿1 + 𝐿2 ± 2𝑀 100= 20 + 60 + 2M M= 10 mH EXAMPLE
  • 17.
    • Stores energyin a magnetic field. • Current-voltage relationship: 𝜈 = 𝐿 ⅆⅈ ⅆ𝑡 . • Energy stored: 𝐸 = 1 2 𝐿𝑖2 . • In DC, Behaves like a short circuit. SYNOPSIS
  • 18.
    THANK YOU FOR STAYINGWITH US THROUGH THE PRESENTATION