Textbook: 8.3, 8.4, 8.5 Homework: pg. 407 #1 – 5 pg. 414 #1 - 4, 6, 9

Slides:



Advertisements
Similar presentations
Topic 6.3: Magnetic force and field
Advertisements

Chapter 30. Induction and Inductance
Magnetism and Currents. A current generates a magnetic field. A magnetic field exerts a force on a current. Two contiguous conductors, carrying currents,
Magnetism Review and tid-bits. Properties of magnets A magnet has polarity - it has a north and a south pole; you cannot isolate the north or the south.
Electromagnetic Induction Inductors. Problem A metal rod of length L and mass m is free to slide, without friction, on two parallel metal tracks. The.
Measuring the strength of a Magnetic Field © David Hoult 2009.
Chapter 32 Magnetic Fields.
Unit 4 Day 8 – Ampere’s Law & Magnetic Fields thru Solenoids & Toroids Definition of Current Ampere’s Law Magnetic Field Inside & Outside a Current Carrying.
Copyright © 2009 Pearson Education, Inc. Lecture 9 – Electromagnetic Induction.
Physics 152 Magnetism Walker, Chapter B Field Outside a Wire Earlier we said that magnetic fields are created by moving charges. A current in a.
Foundations of Physics
AP Physics C Chapter 28.  s1/MovingCharge/MovingCharge.html s1/MovingCharge/MovingCharge.html.
Chapter 29 Electromagnetic Induction and Faraday’s Law HW#9: Chapter 28: Pb.18, Pb. 31, Pb.40 Chapter 29:Pb.3, Pb 30, Pb. 48 Due Wednesday 22.
AP Physics C Montwood High School R. Casao
Nov PHYS , Dr. Andrew Brandt PHYS 1444 – Section 003 Lecture #20, Review Part 2 Tues. November Dr. Andrew Brandt HW28 solution.
Magnetism, Electromagnetism, & Electromagnetic Induction
Magnetism 1. 2 Magnetic fields can be caused in three different ways 1. A moving electrical charge such as a wire with current flowing in it 2. By electrons.
Field Lines.
When a current-carrying loop is placed in a magnetic field, the loop tends to rotate such that its normal becomes aligned with the magnetic field.
Fields Model used when force act a distance. Quantity / unit measure.
Chapter 21 Magnetic Forces and Magnetic Fields Magnetic Fields The needle of a compass is permanent magnet that has a north magnetic pole (N) at.
AP Physics C III.D – Magnetic Forces and Fields. The source and direction of magnetic fields.
CHAPTER OUTLINE 30.1 The Biot–Savart Law 30.2 The Magnetic Force Between Two Parallel Conductors 30.3 Ampère’s Law 30.4 The Magnetic Field of a Solenoid.
Thursday March 31, PHYS Dr. Andrew Brandt PHYS 1444 – Section 02 Lecture #16 Thursday Mar 31, 2011 Dr. Andrew Brandt HW7 Ch 27 is due Fri.
Magnetic Fields due to Current in a Wire
Chapter 19: Magnetism Magnets  Magnets Homework assignment : 18,25,38,45,50 Read Chapter 19 carefully especially examples.
Magnetic Fields. Magnetic Fields and Forces a single magnetic pole has never been isolated magnetic poles are always found in pairs Earth itself is a.
7.2 Magnetic Field Strength p. 274 Calculating Magnetic Field Strength A moving charged particle that enters a magnetic field at any direction other than.
Ph126 Spring 2008 Lecture #8 Magnetic Fields Produced by Moving Charges Prof. Gregory Tarl é
Electric Fields Unit 5: Module 1: Electric and Magnetic Fields
1 15. Magnetic field Historical observations indicated that certain materials attract small pieces of iron. In 1820 H. Oersted discovered that a compass.
PHY 102: Lecture Magnetic Field 6.2 Magnetic Force on Moving Charges 6.3 Magnetic Force on Currents 6.4 Magnetic Field Produced by Current.
Magnetism, Electromagnetism, & Electromagnetic Induction.
Problem 4 A metal wire of mass m can slide without friction on two parallel, horizontal, conducting rails. The rails are connected by a generator which.
The Biot-Savart Law. Biot and Savart recognized that a conductor carrying a steady current produces a force on a magnet. Biot and Savart produced an equation.
Chapter 24 Magnetic Fields.
PHY 102: Lecture Magnetic Field
Magnetism, Electromagnetism, & Electromagnetic Induction
PHYS 1902 Electromagnetism: 3 Lecturer: Prof. Geraint F. Lewis
Two questions: (1) How to find the force, F on the electric charge, q excreted by the field E and/or B? (2) How fields E and/or B can be created?
Electricity and Magnetism - Physics 121 Lecture 10 - Sources of Magnetic Fields (Currents) Y&F Chapter 28, Sec Magnetic fields are due to currents.
2.2 ELECTROMAGNETISM 19th November 2012
Magnetic Force.
Chapter 28 Sources of Magnetic Field
Magnetism, Electromagnetism, & Electromagnetic Induction
PHYS 1444 – Section 501 Lecture #16
Magnetism, Electromagnetism, & Electromagnetic Induction
The Millikan Experiment: Determining the Elementary Charge
Chapter 3 Magnetostatics
Lecture 3-5 Faraday’ s Law (pg. 24 – 35)
Section 2: Magnetic Induction
PHYS 1444 – Section 004 Lecture #11
Electricity and Magnetism
Ampère’s Law Figure Arbitrary path enclosing a current, for Ampère’s law. The path is broken down into segments of equal length Δl.
Lecture 9 Magnetic Fields due to Currents Ch. 30
General Physics (PHY 2140) Lecture 15 Electricity and Magnetism
Recap Field perpendicular to current B
Electromagnetic Forces and Fields
Electricity and Magnetism - Physics 121 Lecture 10 - Sources of Magnetic Fields (Currents) Y&F Chapter 28, Sec Magnetic fields are due to currents.
19.7 Magnetic Fields – Long Straight Wire
General Physics (PHY 2140) Lecture 14 Electricity and Magnetism
Magnetism.
Current in a Magnetic Field
Two questions: (1) How to find the force, F on the electric charge, q excreted by the field E and/or B? (2) How fields E and/or B can be created?
Halliday/Resnick/Walker Fundamentals of Physics
Phys102 Lecture 16/17 Ampere's Law
Magnetic Forces on Conductors
Magnets, how do they work?
Magnetism, Electromagnetism, & Electromagnetic Induction
Chapter 28 Sources of Magnetic Field
Presentation transcript:

Textbook: 8.3, 8.4, 8.5 Homework: pg. 407 #1 – 5 pg. 414 #1 - 4, 6, 9 Magnetic Force on a Conductor, Ampere’s Law & Electromagnetic Induction Textbook: 8.3, 8.4, 8.5 Homework: pg. 407 #1 – 5 pg. 414 #1 - 4, 6, 9 pg. 419 #1, 3, 8 Derive magnetic force on a conductor: One charged particle: F = qvBsin(theta) Many charged particles: F = n(qvBsin(theta)) I = nq/del_t (solve for q) v = l/del_t Substitute in and simplify

FM on a Conductor in a Magnetic field: The magnetic force FM [N] on a conductor of length l [m] carrying a current I [A] through a magnetic field B [T] is: Where  is the angle between I and B RHR: Thumb points in direction of +ve I, fingers in direction of B, palm pushes in direction of FM Pg. 405 #1 - 4

Review - around a conductor: Magnetic field strength is proportional to current: Magnetic field strength is inversely proportional to radius: Therefore:

Ampère’s Law Along any closed path through a magnetic field, the sum of the products of the scalar component of B, parallel to the path segment with the length of the segment, is directly proportional to the net electric current passing through the area enclosed by the path.

Ampere’s Law Take a closed path in B Add up B||l around path Sum equals 0I Permeability of free space 0 = 4 x 10-7 Tm/A Ex. Derive magnetic field of a straight line conductor - Take path as circle (B is constant and always points parallel to path) - Sum(B||*del_l) = Sum(B*del_l) - B*Sum(del_l) = B*2*pi*r = mu* I - B = mu*I/(2*pi*r) Pg. 409 #1 Ex. Derive magnetic field of a solenoid - Take path as rectangle and note: outside solenoid B = 0, and B parallel to solenoid so parts of path equal zero - Only path that remains is inside solenoid in direction of magnetic field - Sum (B||*del_l) = Sum (B*del_l) = B*Sum(del_l) = B*L - Current in rectangle is NI (current from N turns) - B = mu*NI/L Pg. 411 #7

FM between TWO CONDUCTORS Pg 412

Two parallel straight conductors 5 Two parallel straight conductors 5.0 m long and 12 cm apart are to have equal currents. The force each conductor experiences from the other is not to exceed 2.0 x 10-2 N. What is the maximum possible current in each conductor? 49 A

Applications Coaxial Cable (see pg. 410) Definition of Ampere/Coulomb Electric Shielding Magnetic Shielding Definition of Ampere/Coulomb A current of 1 A in parallel wires 1 m apart in a vacuum creates a force of 2 x 10-7 N per meter 1 C is the charge transported by 1 A in 1 s Coaxial Cable Electric Shielding: An electric field diagram will show that the electric field created by the inner cable will terminate on the outer sleeve and will not continue outside. This shields the electric field. (Demo???) Magnetic Shield: Since a current I flows one way and an equal current I flows the other way the total current through a closed path outside the conductor is zero. Therefore the magnetic field is zero. Coaxial cables do not induce magnetic fields outside them. Pg. 413 #9, 10

Maglev Trains Opposite poles levitate train Guide magnets change polarity to push and pull train Very little friction leads to very high speeds (World Record is 581 km/h)

Electromagnetic Induction A changing electric field (i.e. a current) induces a magnetic field A changing magnetic field induces a current in nearby conductors Examples: Electric Generators Transformers Guitar Pickups

Lenz’s Law The direction of an induced current is such that it opposes the changing magnetic field that created it Pg. 418 #2, 3

Magnitude of the magnetic field strength in the core of the solenoid B is the magnitude of the magnetic field strength in the core of the solenoid, in teslas; I is the current flowing through the coil, in amperes; L is the length of the solenoid, in metres; N is the number of turns on the coil.

Pg 418 # 3 Two magnets are dropped through thin metal rings (Figure 11). One of the rings has a small gap. (a) Will both magnets experience a retarding force? Explain your reasoning (b) Will your answers change if the rings are replaced with long cylinders, one with a long thin gap down one side?