Chapter 3 Inductance and Capacitance Electrical Engineering and Electronics II Scott

1. Find the current (voltage) for a capacitance or inductance given the voltage (current) as a function of time. 2. Compute the capacitances of parallel-plate capacitors. 3. Compute the stored energies in capacitances or inductances. 4. Find the voltages across mutually coupled inductances in terms of the currents. Main Contents

Passive element Resistances—energy-consumption elements energy—storage elements ----inductance and capacitance Capacitors is the circuit property that accounts for energy stored in electric fields. Inductors is the circuit property that accounts for energy stored in magnetic fields.

3.1 CAPACITANCE C: unit-F, μF, pF

背极电容单指 向会议话筒 油浸纸电容式套管 耦合电容 超级电容公交车电源 电容性话筒 空调电容 高压电容补偿箱 3.1 CAPACITANCE

Stored charge in terms of voltage Capacitance acts as open circuits for steady dc voltages. C u(t)u(t) i(t)i(t) Passive reference configuration 3.1 CAPACITANCE

Determining current for a capacitance given voltage Example 3.1 Suppose the voltage v(t) is applied to a 1μF capacitance. Plot the stored charge and the current through the capacitance versus time.

Example 3.2 Suppose the current i(t) is applied to a 0.1μF capacitance. The initial charge on it is q(t)=0. Plot the i(t), q(t) and v(t).

Stored energy The power delivered to a circuit element is the product of the current and the voltage provided that the references have the passive configuration. The energy:

Energy flows in capacitor Energy flows out of capacitor Example 3.3 The voltage is applied to a 10μF capacitance. Plot the voltage, power, and stored energy to scale versus time for t between 0 and 5s.

Capacitors in parallel are combined like resistances in series. 3.2 Capacitances in Series and Parallel Capacitances in Parallel

Capacitors in series are combined like resistances in parallel. Capacitances in series 3.2 Capacitances in Series and Parallel

3.3 Physical Characteristics of Capacitors Relative dielectric constant, 相对介电常数 Vaccum dielectric constant, 真空介电常数 Capacitance of the Parallel-Plate Capacitor

Practical Capacitors Real capacitors have maximum voltage ratings.

How to describe the charging or discharging process of capacitance?

3.4 Inductance 螺线管线圈 铁心线圈 铁氧体线圈

贴片电感 标准电感 棒形电感 环形电感 新型电感镇流器 电子变压器 3.4 Inductance

单相变压器 试验变压器 三相变压器 心式变压器的内部结构 3.4 Inductance

电磁调速异步电动机 三相自动扶梯用异步电动机变频调速异步电动机 三相异步电动机 3.4 Inductance

同步电动机 交流伺服电动机 BC 系列反应式步进电动机 3.4 Inductance

交流接触器 3.4 Inductance

Voltage is proportional to the time rate of change of current Passive reference configuration 3.4 Inductance

Current in terms of voltage Power and Energy for a capacitor

Example 3.6 The current flows through a 5H inductance. Plot the voltage, power, and stored energy to scale versus time for t between 0 and 5s.

Example 3.7 We have a switch that close at t=0, connecting a 10 V source to a 2-H inductance. Find the current as a function of time.

How to describe the charging or discharging process of Inductance?

3.5 Inductances in Series and Parallel

Exercise 3.10 Find the equivalent inductance for each of the circuits.

3.7 Mutual Inductance Self Inductance, 自感

变压器 非磁性棒 铁心 原（一次）绕组 副（二次）绕组 3.7 Mutual Inductance

Page 137 Practical application 3.1 Electronic Photo Flash To finish the group table, 4~5 persons in every group and select a leader. To write down the main idea of Practical application 3.1 in Word document and send it to by To describe to main idea and answer some questions. Teamwork 2