lecture 9: inductors & capacitors nilsson & riedel 6.1-6.3
DESCRIPTION
Lecture 9: Inductors & Capacitors Nilsson & Riedel 6.1-6.3. ENG17 (Sec. 2): Circuits I Spring 2014. April 29, 2014. Overview. Inductors Capacitors Series-Parallel L/C. Inductance in the Real World. What Does an Inductor Look Like?. What Does an Inductor Do?. - PowerPoint PPT PresentationTRANSCRIPT
1
Lecture 9:Inductors & CapacitorsNilsson & Riedel 6.1-6.3
ENG17 (Sec. 2): Circuits I
Spring 2014
April 29, 2014
2
Overview
• Inductors• Capacitors• Series-Parallel L/C
3
Inductance in the Real World
4
What Does an Inductor Look Like?
5
What Does an Inductor Do?
• Inductor: electrical component that opposes any change in electrical current
• Associates electrical current and magnetic fields
• Magnetic field generated by charge in motion (i.e., current)
• If current changes wrt time, mag field changes wrt time– Varying mag field results in voltage in linked
conductor
6
Add’l Note
• Inductors can store energy through the mag fields– Used in spark plugs
• Inductors do not generate energy, so they are still passive devices
7
Inductors in Circuits
Symbol: LUnits: [H] for henrys = [Wb/A]
𝑣=𝐿𝑑𝑖𝑑𝑡
8
Determining Voltage
9
Current in Inductor
𝑖 (𝑡 )= 1𝐿∫𝑡0
𝑡
𝑣 𝑑𝜏+𝑖(𝑡 0)
10
Power & Energy in Inductor
𝑝=𝐿𝑖𝑑𝑖𝑑𝑡
𝑤=12𝐿𝑖2
11
Overview
• Inductors• Capacitors• Series-Parallel L/C
12
Capacitance in the Real World
13
What Does a Capacitor Look Like?
14
What Does a Capacitor Do?
• Capacitor: electrical component that consists of 2 conductors separated by dielectric
• “Stores” electric charge (like a battery)• Associated with electric fields, due to
separation of charge (voltage)• If voltage varies with time, E-field varies with
time– Varying E-field generates displacement current in
space occupied by field– Capacitance relates displacement current to voltage
15
Capacitors in Circuits
Symbol: CUnits: [F] for farads = [C/V]
𝑖=𝐶𝑑𝑣𝑑𝑡
16
Capacitor Voltage, Power, & Energy
𝑣 (𝑡 )= 1𝐶∫
𝑡 0
𝑡
𝑖𝑑𝜏+𝑣(𝑡0)
𝑝=𝑣𝑖=𝐶𝑣𝑑𝑣𝑑𝑡
𝑤=12𝐶𝑣2
17
Example
𝑣 (𝑡 )={ 0 ,𝑡≤0 𝑠4 𝑡 ,0𝑠≤ 𝑡≤1𝑠4𝑒−(𝑡− 1) ,𝑡≥1𝑠
18
Overview
• Inductors• Capacitors• Series-Parallel L/C
19
Inductors Series-Parallel
Series Parallel
20
Capacitors Series-Parallel
Series Parallel
21
Recap
• Inductors• Capacitors• Series-Parallel L/C