lect20-nov14 - Physics 227: Exam 2 Information! Exam 2: 16...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Physics 227: Exam 2 Information Exam 2: 16 questions covering chapters 25 – 28 Thursday, Nov 17, 2011, 9:40 PM - 11:00 PM Room assignments: A-I ARC 103 J-M SEC 111 (may start late) N-R PLH S-Z Beck Auditorium, Livingston Campus!!! ( NOT Hill 114 ) Anyone with a conFict should contact Prof. Cizewski [email protected] TODAY!! Bring pencils, one formula sheet w/ anything you want NO calculators, NO cell phones, NO electronics needed or allowed!
Background image of page 1

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

View Full DocumentRight Arrow Icon
Outline Lecture 20 Review of Lecture 19 & Faraday’s law Self inductance and inductors How a time-varying current in one coil can induce an emf How to relate the induced emf in a circuit to the rate of change of current in the same circuit The R-L circuit: how to analyze circuits that include both a resistor and an inductor (coil) Magnetic field energy – how to calculate the energy stored in a magnetic field
Background image of page 2
Maxwell’s equations Gauss’s Law for E Gauss’s Law for B Ampere’s Law (conduction + displacement currents) Faraday’s Law Lecture 19 Review E d A = q enclosed ε 0 B d A = 0 (no magnetic charges) E d = d Φ B dt B d = μ 0 ( i conduction + 0 d Φ E dt ) enclosed where 1 0 μ 0 = c
Background image of page 3

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

View Full DocumentRight Arrow Icon
Faraday’s Law: If change in magnetic ±ux, then EMF is induced Physics 227: Lecture 20 EMF = d Φ B dt where Φ B = B d A = BA cos θ (if B is uniform over A) Note minus sign (Lenz’s Law): self-induced EMF opposes change in current Faraday’s Law PhET
Background image of page 4
Previous assumption not quite correct: When switch closed I ε /R immediately Faraday’s law prevents from happening Rather, as current increases vs time, Φ Β due to this current also increases This increasing ±ux induces EMF that opposes change in Φ Β => opposing EMF means gradual increase in the current This effect = SELF-INDUCTION Isolated circuit and induced EMF EMF = d Φ B dt = d dt BA Isolated circuit: switch, resistor, source of EMF Induced EMF
Background image of page 5

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

View Full DocumentRight Arrow Icon
When switch closed I ε /R immediately Faraday’s law prevents from happening Rather, as current increases vs time, Φ Β due to this current also increases This effect = SELF-INDUCTION = L Isolated circuit and induced EMF EMF induced = N d Φ B dt = L di dt L = N Φ B i Isolated circuit: switch, resistor, source of EMF Assume same ±ux through all N turns Inductance depends upon geometry
Background image of page 6
Purpose of inductor: oppose any variations in the current through the circuit; Unit of inductance = Henry = Volt-second/Ampere Examples: Inductor in a DC circuit helps to maintain a steady current despite Fuctuations in the applied EM± Inductor in an AC circuit tends to suppress variations of the current that are more rapid than desired Inductors are circuit elements
Background image of page 7

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

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/03/2012 for the course PHYSICS 750:227 taught by Professor Ronaldgilman during the Fall '11 term at Rutgers.

Page1 / 31

lect20-nov14 - Physics 227: Exam 2 Information! Exam 2: 16...

This preview shows document pages 1 - 8. Sign up to view the full document.

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