Lecture 21 preview mar25

Lecture 21 preview mar25 - Lecture 21: LR, LC, and LRC...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Lecture 21: LR, LC, and LRC circuits Finish Ch 30 today Thursday: begin AC circuits, Ch 31 Exam next week through Thursday’s material
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Energy stored in “charging” an inductor L in stored energy U LI Lidi Pdt W low is i when low dt di iL i P I ext ext = = = = = = 2 0 2 1 ) ( ξ If we increase current from 0 to I in an inductor work must be done against the opposing emf, ξ = -Ldi/dt. This is similar to charging a battery. The power required of some external emf is: We say U is stored in the B field SOLENOID: 0 2 2 0 0 2 2 0 2 2 1 2 1 μ B Al U u density B Al U l NI B and I l A N U sol B sol sol sol = = = = = Energy Density, u B compare with u E =(1/2)ε 0 E 2
Background image of page 2
Inductors in circuits (we have R and C, now we add L) i increasing ξ + - ΔV in direction of I is negative ΔV = -Ldi/dt i decreasing ξ - + ΔV in direction of I is positive ΔV = -Ldi/dt So, in the direction of current ΔV = -Ldi/dt. Let’s use Kirchhoff’s loop rule
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Current buildup in the LR circuit (take a walk around Kirchhoff’s loop) ξ = + = - - iR dt di L dt di L iR 0
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 11

Lecture 21 preview mar25 - Lecture 21: LR, LC, and LRC...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online